1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *
4 * Copyright (C) 2011 Novell Inc.
5 */
6
7#include <linux/fs.h>
8#include <linux/slab.h>
9#include <linux/namei.h>
10#include <linux/file.h>
11#include <linux/xattr.h>
12#include <linux/rbtree.h>
13#include <linux/security.h>
14#include <linux/cred.h>
15#include <linux/ratelimit.h>
16#include "overlayfs.h"
17
18struct ovl_cache_entry {
19 unsigned int len;
20 unsigned int type;
21 u64 real_ino;
22 u64 ino;
23 struct list_head l_node;
24 struct rb_node node;
25 struct ovl_cache_entry *next_maybe_whiteout;
26 bool is_upper;
27 bool is_whiteout;
28 bool check_xwhiteout;
29 char name[];
30};
31
32struct ovl_dir_cache {
33 long refcount;
34 u64 version;
35 struct list_head entries;
36 struct rb_root root;
37};
38
39struct ovl_readdir_data {
40 struct dir_context ctx;
41 struct dentry *dentry;
42 bool is_lowest;
43 struct rb_root *root;
44 struct list_head *list;
45 struct list_head middle;
46 struct ovl_cache_entry *first_maybe_whiteout;
47 int count;
48 int err;
49 bool is_upper;
50 bool d_type_supported;
51 bool in_xwhiteouts_dir;
52};
53
54struct ovl_dir_file {
55 bool is_real;
56 bool is_upper;
57 struct ovl_dir_cache *cache;
58 struct list_head *cursor;
59 struct file *realfile;
60 struct file *upperfile;
61};
62
63static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
64{
65 return rb_entry(n, struct ovl_cache_entry, node);
66}
67
68static bool ovl_cache_entry_find_link(const char *name, int len,
69 struct rb_node ***link,
70 struct rb_node **parent)
71{
72 bool found = false;
73 struct rb_node **newp = *link;
74
75 while (!found && *newp) {
76 int cmp;
77 struct ovl_cache_entry *tmp;
78
79 *parent = *newp;
80 tmp = ovl_cache_entry_from_node(n: *newp);
81 cmp = strncmp(name, tmp->name, len);
82 if (cmp > 0)
83 newp = &tmp->node.rb_right;
84 else if (cmp < 0 || len < tmp->len)
85 newp = &tmp->node.rb_left;
86 else
87 found = true;
88 }
89 *link = newp;
90
91 return found;
92}
93
94static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
95 const char *name, int len)
96{
97 struct rb_node *node = root->rb_node;
98 int cmp;
99
100 while (node) {
101 struct ovl_cache_entry *p = ovl_cache_entry_from_node(n: node);
102
103 cmp = strncmp(name, p->name, len);
104 if (cmp > 0)
105 node = p->node.rb_right;
106 else if (cmp < 0 || len < p->len)
107 node = p->node.rb_left;
108 else
109 return p;
110 }
111
112 return NULL;
113}
114
115static bool ovl_calc_d_ino(struct ovl_readdir_data *rdd,
116 struct ovl_cache_entry *p)
117{
118 /* Don't care if not doing ovl_iter() */
119 if (!rdd->dentry)
120 return false;
121
122 /* Always recalc d_ino when remapping lower inode numbers */
123 if (ovl_xino_bits(ofs: OVL_FS(sb: rdd->dentry->d_sb)))
124 return true;
125
126 /* Always recalc d_ino for parent */
127 if (strcmp(p->name, "..") == 0)
128 return true;
129
130 /* If this is lower, then native d_ino will do */
131 if (!rdd->is_upper)
132 return false;
133
134 /*
135 * Recalc d_ino for '.' and for all entries if dir is impure (contains
136 * copied up entries)
137 */
138 if ((p->name[0] == '.' && p->len == 1) ||
139 ovl_test_flag(flag: OVL_IMPURE, inode: d_inode(dentry: rdd->dentry)))
140 return true;
141
142 return false;
143}
144
145static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd,
146 const char *name, int len,
147 u64 ino, unsigned int d_type)
148{
149 struct ovl_cache_entry *p;
150 size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);
151
152 p = kmalloc(size, GFP_KERNEL);
153 if (!p)
154 return NULL;
155
156 memcpy(p->name, name, len);
157 p->name[len] = '\0';
158 p->len = len;
159 p->type = d_type;
160 p->real_ino = ino;
161 p->ino = ino;
162 /* Defer setting d_ino for upper entry to ovl_iterate() */
163 if (ovl_calc_d_ino(rdd, p))
164 p->ino = 0;
165 p->is_upper = rdd->is_upper;
166 p->is_whiteout = false;
167 /* Defer check for overlay.whiteout to ovl_iterate() */
168 p->check_xwhiteout = rdd->in_xwhiteouts_dir && d_type == DT_REG;
169
170 if (d_type == DT_CHR) {
171 p->next_maybe_whiteout = rdd->first_maybe_whiteout;
172 rdd->first_maybe_whiteout = p;
173 }
174 return p;
175}
176
177static bool ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
178 const char *name, int len, u64 ino,
179 unsigned int d_type)
180{
181 struct rb_node **newp = &rdd->root->rb_node;
182 struct rb_node *parent = NULL;
183 struct ovl_cache_entry *p;
184
185 if (ovl_cache_entry_find_link(name, len, link: &newp, parent: &parent))
186 return true;
187
188 p = ovl_cache_entry_new(rdd, name, len, ino, d_type);
189 if (p == NULL) {
190 rdd->err = -ENOMEM;
191 return false;
192 }
193
194 list_add_tail(new: &p->l_node, head: rdd->list);
195 rb_link_node(node: &p->node, parent, rb_link: newp);
196 rb_insert_color(&p->node, rdd->root);
197
198 return true;
199}
200
201static bool ovl_fill_lowest(struct ovl_readdir_data *rdd,
202 const char *name, int namelen,
203 loff_t offset, u64 ino, unsigned int d_type)
204{
205 struct ovl_cache_entry *p;
206
207 p = ovl_cache_entry_find(root: rdd->root, name, len: namelen);
208 if (p) {
209 list_move_tail(list: &p->l_node, head: &rdd->middle);
210 } else {
211 p = ovl_cache_entry_new(rdd, name, len: namelen, ino, d_type);
212 if (p == NULL)
213 rdd->err = -ENOMEM;
214 else
215 list_add_tail(new: &p->l_node, head: &rdd->middle);
216 }
217
218 return rdd->err == 0;
219}
220
221void ovl_cache_free(struct list_head *list)
222{
223 struct ovl_cache_entry *p;
224 struct ovl_cache_entry *n;
225
226 list_for_each_entry_safe(p, n, list, l_node)
227 kfree(objp: p);
228
229 INIT_LIST_HEAD(list);
230}
231
232void ovl_dir_cache_free(struct inode *inode)
233{
234 struct ovl_dir_cache *cache = ovl_dir_cache(inode);
235
236 if (cache) {
237 ovl_cache_free(list: &cache->entries);
238 kfree(objp: cache);
239 }
240}
241
242static void ovl_cache_put(struct ovl_dir_file *od, struct inode *inode)
243{
244 struct ovl_dir_cache *cache = od->cache;
245
246 WARN_ON(cache->refcount <= 0);
247 cache->refcount--;
248 if (!cache->refcount) {
249 if (ovl_dir_cache(inode) == cache)
250 ovl_set_dir_cache(inode, NULL);
251
252 ovl_cache_free(list: &cache->entries);
253 kfree(objp: cache);
254 }
255}
256
257static bool ovl_fill_merge(struct dir_context *ctx, const char *name,
258 int namelen, loff_t offset, u64 ino,
259 unsigned int d_type)
260{
261 struct ovl_readdir_data *rdd =
262 container_of(ctx, struct ovl_readdir_data, ctx);
263
264 rdd->count++;
265 if (!rdd->is_lowest)
266 return ovl_cache_entry_add_rb(rdd, name, len: namelen, ino, d_type);
267 else
268 return ovl_fill_lowest(rdd, name, namelen, offset, ino, d_type);
269}
270
271static int ovl_check_whiteouts(const struct path *path, struct ovl_readdir_data *rdd)
272{
273 int err;
274 struct ovl_cache_entry *p;
275 struct dentry *dentry, *dir = path->dentry;
276 const struct cred *old_cred;
277
278 old_cred = ovl_override_creds(sb: rdd->dentry->d_sb);
279
280 err = down_write_killable(sem: &dir->d_inode->i_rwsem);
281 if (!err) {
282 while (rdd->first_maybe_whiteout) {
283 p = rdd->first_maybe_whiteout;
284 rdd->first_maybe_whiteout = p->next_maybe_whiteout;
285 dentry = lookup_one(mnt_idmap(mnt: path->mnt), p->name, dir, p->len);
286 if (!IS_ERR(ptr: dentry)) {
287 p->is_whiteout = ovl_is_whiteout(dentry);
288 dput(dentry);
289 }
290 }
291 inode_unlock(inode: dir->d_inode);
292 }
293 revert_creds(old_cred);
294
295 return err;
296}
297
298static inline int ovl_dir_read(const struct path *realpath,
299 struct ovl_readdir_data *rdd)
300{
301 struct file *realfile;
302 int err;
303
304 realfile = ovl_path_open(path: realpath, O_RDONLY | O_LARGEFILE);
305 if (IS_ERR(ptr: realfile))
306 return PTR_ERR(ptr: realfile);
307
308 rdd->in_xwhiteouts_dir = rdd->dentry &&
309 ovl_path_check_xwhiteouts_xattr(ofs: OVL_FS(sb: rdd->dentry->d_sb), path: realpath);
310 rdd->first_maybe_whiteout = NULL;
311 rdd->ctx.pos = 0;
312 do {
313 rdd->count = 0;
314 rdd->err = 0;
315 err = iterate_dir(realfile, &rdd->ctx);
316 if (err >= 0)
317 err = rdd->err;
318 } while (!err && rdd->count);
319
320 if (!err && rdd->first_maybe_whiteout && rdd->dentry)
321 err = ovl_check_whiteouts(path: realpath, rdd);
322
323 fput(realfile);
324
325 return err;
326}
327
328static void ovl_dir_reset(struct file *file)
329{
330 struct ovl_dir_file *od = file->private_data;
331 struct ovl_dir_cache *cache = od->cache;
332 struct inode *inode = file_inode(f: file);
333 bool is_real;
334
335 if (cache && ovl_inode_version_get(inode) != cache->version) {
336 ovl_cache_put(od, inode);
337 od->cache = NULL;
338 od->cursor = NULL;
339 }
340 is_real = ovl_dir_is_real(dir: inode);
341 if (od->is_real != is_real) {
342 /* is_real can only become false when dir is copied up */
343 if (WARN_ON(is_real))
344 return;
345 od->is_real = false;
346 }
347}
348
349static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list,
350 struct rb_root *root)
351{
352 int err;
353 struct path realpath;
354 struct ovl_readdir_data rdd = {
355 .ctx.actor = ovl_fill_merge,
356 .dentry = dentry,
357 .list = list,
358 .root = root,
359 .is_lowest = false,
360 };
361 int idx, next;
362
363 for (idx = 0; idx != -1; idx = next) {
364 next = ovl_path_next(idx, dentry, path: &realpath);
365 rdd.is_upper = ovl_dentry_upper(dentry) == realpath.dentry;
366
367 if (next != -1) {
368 err = ovl_dir_read(realpath: &realpath, rdd: &rdd);
369 if (err)
370 break;
371 } else {
372 /*
373 * Insert lowest layer entries before upper ones, this
374 * allows offsets to be reasonably constant
375 */
376 list_add(new: &rdd.middle, head: rdd.list);
377 rdd.is_lowest = true;
378 err = ovl_dir_read(realpath: &realpath, rdd: &rdd);
379 list_del(entry: &rdd.middle);
380 }
381 }
382 return err;
383}
384
385static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
386{
387 struct list_head *p;
388 loff_t off = 0;
389
390 list_for_each(p, &od->cache->entries) {
391 if (off >= pos)
392 break;
393 off++;
394 }
395 /* Cursor is safe since the cache is stable */
396 od->cursor = p;
397}
398
399static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
400{
401 int res;
402 struct ovl_dir_cache *cache;
403 struct inode *inode = d_inode(dentry);
404
405 cache = ovl_dir_cache(inode);
406 if (cache && ovl_inode_version_get(inode) == cache->version) {
407 WARN_ON(!cache->refcount);
408 cache->refcount++;
409 return cache;
410 }
411 ovl_set_dir_cache(inode: d_inode(dentry), NULL);
412
413 cache = kzalloc(size: sizeof(struct ovl_dir_cache), GFP_KERNEL);
414 if (!cache)
415 return ERR_PTR(error: -ENOMEM);
416
417 cache->refcount = 1;
418 INIT_LIST_HEAD(list: &cache->entries);
419 cache->root = RB_ROOT;
420
421 res = ovl_dir_read_merged(dentry, list: &cache->entries, root: &cache->root);
422 if (res) {
423 ovl_cache_free(list: &cache->entries);
424 kfree(objp: cache);
425 return ERR_PTR(error: res);
426 }
427
428 cache->version = ovl_inode_version_get(inode);
429 ovl_set_dir_cache(inode, cache);
430
431 return cache;
432}
433
434/* Map inode number to lower fs unique range */
435static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid,
436 const char *name, int namelen, bool warn)
437{
438 unsigned int xinoshift = 64 - xinobits;
439
440 if (unlikely(ino >> xinoshift)) {
441 if (warn) {
442 pr_warn_ratelimited("d_ino too big (%.*s, ino=%llu, xinobits=%d)\n",
443 namelen, name, ino, xinobits);
444 }
445 return ino;
446 }
447
448 /*
449 * The lowest xinobit is reserved for mapping the non-peresistent inode
450 * numbers range, but this range is only exposed via st_ino, not here.
451 */
452 return ino | ((u64)fsid) << (xinoshift + 1);
453}
454
455/*
456 * Set d_ino for upper entries if needed. Non-upper entries should always report
457 * the uppermost real inode ino and should not call this function.
458 *
459 * When not all layer are on same fs, report real ino also for upper.
460 *
461 * When all layers are on the same fs, and upper has a reference to
462 * copy up origin, call vfs_getattr() on the overlay entry to make
463 * sure that d_ino will be consistent with st_ino from stat(2).
464 *
465 * Also checks the overlay.whiteout xattr by doing a full lookup which will return
466 * negative in this case.
467 */
468static int ovl_cache_update(const struct path *path, struct ovl_cache_entry *p, bool update_ino)
469
470{
471 struct dentry *dir = path->dentry;
472 struct ovl_fs *ofs = OVL_FS(sb: dir->d_sb);
473 struct dentry *this = NULL;
474 enum ovl_path_type type;
475 u64 ino = p->real_ino;
476 int xinobits = ovl_xino_bits(ofs);
477 int err = 0;
478
479 if (!ovl_same_dev(ofs) && !p->check_xwhiteout)
480 goto out;
481
482 if (p->name[0] == '.') {
483 if (p->len == 1) {
484 this = dget(dentry: dir);
485 goto get;
486 }
487 if (p->len == 2 && p->name[1] == '.') {
488 /* we shall not be moved */
489 this = dget(dentry: dir->d_parent);
490 goto get;
491 }
492 }
493 /* This checks also for xwhiteouts */
494 this = lookup_one(mnt_idmap(mnt: path->mnt), p->name, dir, p->len);
495 if (IS_ERR_OR_NULL(ptr: this) || !this->d_inode) {
496 /* Mark a stale entry */
497 p->is_whiteout = true;
498 if (IS_ERR(ptr: this)) {
499 err = PTR_ERR(ptr: this);
500 this = NULL;
501 goto fail;
502 }
503 goto out;
504 }
505
506get:
507 if (!ovl_same_dev(ofs) || !update_ino)
508 goto out;
509
510 type = ovl_path_type(dentry: this);
511 if (OVL_TYPE_ORIGIN(type)) {
512 struct kstat stat;
513 struct path statpath = *path;
514
515 statpath.dentry = this;
516 err = vfs_getattr(&statpath, &stat, STATX_INO, 0);
517 if (err)
518 goto fail;
519
520 /*
521 * Directory inode is always on overlay st_dev.
522 * Non-dir with ovl_same_dev() could be on pseudo st_dev in case
523 * of xino bits overflow.
524 */
525 WARN_ON_ONCE(S_ISDIR(stat.mode) &&
526 dir->d_sb->s_dev != stat.dev);
527 ino = stat.ino;
528 } else if (xinobits && !OVL_TYPE_UPPER(type)) {
529 ino = ovl_remap_lower_ino(ino, xinobits,
530 fsid: ovl_layer_lower(dentry: this)->fsid,
531 name: p->name, namelen: p->len,
532 warn: ovl_xino_warn(ofs));
533 }
534
535out:
536 p->ino = ino;
537 dput(this);
538 return err;
539
540fail:
541 pr_warn_ratelimited("failed to look up (%s) for ino (%i)\n",
542 p->name, err);
543 goto out;
544}
545
546static bool ovl_fill_plain(struct dir_context *ctx, const char *name,
547 int namelen, loff_t offset, u64 ino,
548 unsigned int d_type)
549{
550 struct ovl_cache_entry *p;
551 struct ovl_readdir_data *rdd =
552 container_of(ctx, struct ovl_readdir_data, ctx);
553
554 rdd->count++;
555 p = ovl_cache_entry_new(rdd, name, len: namelen, ino, d_type);
556 if (p == NULL) {
557 rdd->err = -ENOMEM;
558 return false;
559 }
560 list_add_tail(new: &p->l_node, head: rdd->list);
561
562 return true;
563}
564
565static int ovl_dir_read_impure(const struct path *path, struct list_head *list,
566 struct rb_root *root)
567{
568 int err;
569 struct path realpath;
570 struct ovl_cache_entry *p, *n;
571 struct ovl_readdir_data rdd = {
572 .ctx.actor = ovl_fill_plain,
573 .list = list,
574 .root = root,
575 };
576
577 INIT_LIST_HEAD(list);
578 *root = RB_ROOT;
579 ovl_path_upper(dentry: path->dentry, path: &realpath);
580
581 err = ovl_dir_read(realpath: &realpath, rdd: &rdd);
582 if (err)
583 return err;
584
585 list_for_each_entry_safe(p, n, list, l_node) {
586 if (strcmp(p->name, ".") != 0 &&
587 strcmp(p->name, "..") != 0) {
588 err = ovl_cache_update(path, p, update_ino: true);
589 if (err)
590 return err;
591 }
592 if (p->ino == p->real_ino) {
593 list_del(entry: &p->l_node);
594 kfree(objp: p);
595 } else {
596 struct rb_node **newp = &root->rb_node;
597 struct rb_node *parent = NULL;
598
599 if (WARN_ON(ovl_cache_entry_find_link(p->name, p->len,
600 &newp, &parent)))
601 return -EIO;
602
603 rb_link_node(node: &p->node, parent, rb_link: newp);
604 rb_insert_color(&p->node, root);
605 }
606 }
607 return 0;
608}
609
610static struct ovl_dir_cache *ovl_cache_get_impure(const struct path *path)
611{
612 int res;
613 struct dentry *dentry = path->dentry;
614 struct inode *inode = d_inode(dentry);
615 struct ovl_fs *ofs = OVL_FS(sb: dentry->d_sb);
616 struct ovl_dir_cache *cache;
617
618 cache = ovl_dir_cache(inode);
619 if (cache && ovl_inode_version_get(inode) == cache->version)
620 return cache;
621
622 /* Impure cache is not refcounted, free it here */
623 ovl_dir_cache_free(inode);
624 ovl_set_dir_cache(inode, NULL);
625
626 cache = kzalloc(size: sizeof(struct ovl_dir_cache), GFP_KERNEL);
627 if (!cache)
628 return ERR_PTR(error: -ENOMEM);
629
630 res = ovl_dir_read_impure(path, list: &cache->entries, root: &cache->root);
631 if (res) {
632 ovl_cache_free(list: &cache->entries);
633 kfree(objp: cache);
634 return ERR_PTR(error: res);
635 }
636 if (list_empty(head: &cache->entries)) {
637 /*
638 * A good opportunity to get rid of an unneeded "impure" flag.
639 * Removing the "impure" xattr is best effort.
640 */
641 if (!ovl_want_write(dentry)) {
642 ovl_removexattr(ofs, dentry: ovl_dentry_upper(dentry),
643 ox: OVL_XATTR_IMPURE);
644 ovl_drop_write(dentry);
645 }
646 ovl_clear_flag(flag: OVL_IMPURE, inode);
647 kfree(objp: cache);
648 return NULL;
649 }
650
651 cache->version = ovl_inode_version_get(inode);
652 ovl_set_dir_cache(inode, cache);
653
654 return cache;
655}
656
657struct ovl_readdir_translate {
658 struct dir_context *orig_ctx;
659 struct ovl_dir_cache *cache;
660 struct dir_context ctx;
661 u64 parent_ino;
662 int fsid;
663 int xinobits;
664 bool xinowarn;
665};
666
667static bool ovl_fill_real(struct dir_context *ctx, const char *name,
668 int namelen, loff_t offset, u64 ino,
669 unsigned int d_type)
670{
671 struct ovl_readdir_translate *rdt =
672 container_of(ctx, struct ovl_readdir_translate, ctx);
673 struct dir_context *orig_ctx = rdt->orig_ctx;
674
675 if (rdt->parent_ino && strcmp(name, "..") == 0) {
676 ino = rdt->parent_ino;
677 } else if (rdt->cache) {
678 struct ovl_cache_entry *p;
679
680 p = ovl_cache_entry_find(root: &rdt->cache->root, name, len: namelen);
681 if (p)
682 ino = p->ino;
683 } else if (rdt->xinobits) {
684 ino = ovl_remap_lower_ino(ino, xinobits: rdt->xinobits, fsid: rdt->fsid,
685 name, namelen, warn: rdt->xinowarn);
686 }
687
688 return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
689}
690
691static bool ovl_is_impure_dir(struct file *file)
692{
693 struct ovl_dir_file *od = file->private_data;
694 struct inode *dir = file_inode(f: file);
695
696 /*
697 * Only upper dir can be impure, but if we are in the middle of
698 * iterating a lower real dir, dir could be copied up and marked
699 * impure. We only want the impure cache if we started iterating
700 * a real upper dir to begin with.
701 */
702 return od->is_upper && ovl_test_flag(flag: OVL_IMPURE, inode: dir);
703
704}
705
706static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
707{
708 int err;
709 struct ovl_dir_file *od = file->private_data;
710 struct dentry *dir = file->f_path.dentry;
711 struct ovl_fs *ofs = OVL_FS(sb: dir->d_sb);
712 const struct ovl_layer *lower_layer = ovl_layer_lower(dentry: dir);
713 struct ovl_readdir_translate rdt = {
714 .ctx.actor = ovl_fill_real,
715 .orig_ctx = ctx,
716 .xinobits = ovl_xino_bits(ofs),
717 .xinowarn = ovl_xino_warn(ofs),
718 };
719
720 if (rdt.xinobits && lower_layer)
721 rdt.fsid = lower_layer->fsid;
722
723 if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) {
724 struct kstat stat;
725 struct path statpath = file->f_path;
726
727 statpath.dentry = dir->d_parent;
728 err = vfs_getattr(&statpath, &stat, STATX_INO, 0);
729 if (err)
730 return err;
731
732 WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
733 rdt.parent_ino = stat.ino;
734 }
735
736 if (ovl_is_impure_dir(file)) {
737 rdt.cache = ovl_cache_get_impure(path: &file->f_path);
738 if (IS_ERR(ptr: rdt.cache))
739 return PTR_ERR(ptr: rdt.cache);
740 }
741
742 err = iterate_dir(od->realfile, &rdt.ctx);
743 ctx->pos = rdt.ctx.pos;
744
745 return err;
746}
747
748
749static int ovl_iterate(struct file *file, struct dir_context *ctx)
750{
751 struct ovl_dir_file *od = file->private_data;
752 struct dentry *dentry = file->f_path.dentry;
753 struct ovl_fs *ofs = OVL_FS(sb: dentry->d_sb);
754 struct ovl_cache_entry *p;
755 const struct cred *old_cred;
756 int err;
757
758 old_cred = ovl_override_creds(sb: dentry->d_sb);
759 if (!ctx->pos)
760 ovl_dir_reset(file);
761
762 if (od->is_real) {
763 /*
764 * If parent is merge, then need to adjust d_ino for '..', if
765 * dir is impure then need to adjust d_ino for copied up
766 * entries.
767 */
768 if (ovl_xino_bits(ofs) ||
769 (ovl_same_fs(ofs) &&
770 (ovl_is_impure_dir(file) ||
771 OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
772 err = ovl_iterate_real(file, ctx);
773 } else {
774 err = iterate_dir(od->realfile, ctx);
775 }
776 goto out;
777 }
778
779 if (!od->cache) {
780 struct ovl_dir_cache *cache;
781
782 cache = ovl_cache_get(dentry);
783 err = PTR_ERR(ptr: cache);
784 if (IS_ERR(ptr: cache))
785 goto out;
786
787 od->cache = cache;
788 ovl_seek_cursor(od, pos: ctx->pos);
789 }
790
791 while (od->cursor != &od->cache->entries) {
792 p = list_entry(od->cursor, struct ovl_cache_entry, l_node);
793 if (!p->is_whiteout) {
794 if (!p->ino || p->check_xwhiteout) {
795 err = ovl_cache_update(path: &file->f_path, p, update_ino: !p->ino);
796 if (err)
797 goto out;
798 }
799 }
800 /* ovl_cache_update() sets is_whiteout on stale entry */
801 if (!p->is_whiteout) {
802 if (!dir_emit(ctx, name: p->name, namelen: p->len, ino: p->ino, type: p->type))
803 break;
804 }
805 od->cursor = p->l_node.next;
806 ctx->pos++;
807 }
808 err = 0;
809out:
810 revert_creds(old_cred);
811 return err;
812}
813
814static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
815{
816 loff_t res;
817 struct ovl_dir_file *od = file->private_data;
818
819 inode_lock(inode: file_inode(f: file));
820 if (!file->f_pos)
821 ovl_dir_reset(file);
822
823 if (od->is_real) {
824 res = vfs_llseek(file: od->realfile, offset, whence: origin);
825 file->f_pos = od->realfile->f_pos;
826 } else {
827 res = -EINVAL;
828
829 switch (origin) {
830 case SEEK_CUR:
831 offset += file->f_pos;
832 break;
833 case SEEK_SET:
834 break;
835 default:
836 goto out_unlock;
837 }
838 if (offset < 0)
839 goto out_unlock;
840
841 if (offset != file->f_pos) {
842 file->f_pos = offset;
843 if (od->cache)
844 ovl_seek_cursor(od, pos: offset);
845 }
846 res = offset;
847 }
848out_unlock:
849 inode_unlock(inode: file_inode(f: file));
850
851 return res;
852}
853
854static struct file *ovl_dir_open_realfile(const struct file *file,
855 const struct path *realpath)
856{
857 struct file *res;
858 const struct cred *old_cred;
859
860 old_cred = ovl_override_creds(sb: file_inode(f: file)->i_sb);
861 res = ovl_path_open(path: realpath, O_RDONLY | (file->f_flags & O_LARGEFILE));
862 revert_creds(old_cred);
863
864 return res;
865}
866
867/*
868 * Like ovl_real_fdget(), returns upperfile if dir was copied up since open.
869 * Unlike ovl_real_fdget(), this caches upperfile in file->private_data.
870 *
871 * TODO: use same abstract type for file->private_data of dir and file so
872 * upperfile could also be cached for files as well.
873 */
874struct file *ovl_dir_real_file(const struct file *file, bool want_upper)
875{
876
877 struct ovl_dir_file *od = file->private_data;
878 struct dentry *dentry = file->f_path.dentry;
879 struct file *old, *realfile = od->realfile;
880
881 if (!OVL_TYPE_UPPER(ovl_path_type(dentry)))
882 return want_upper ? NULL : realfile;
883
884 /*
885 * Need to check if we started out being a lower dir, but got copied up
886 */
887 if (!od->is_upper) {
888 realfile = READ_ONCE(od->upperfile);
889 if (!realfile) {
890 struct path upperpath;
891
892 ovl_path_upper(dentry, path: &upperpath);
893 realfile = ovl_dir_open_realfile(file, realpath: &upperpath);
894 if (IS_ERR(ptr: realfile))
895 return realfile;
896
897 old = cmpxchg_release(&od->upperfile, NULL, realfile);
898 if (old) {
899 fput(realfile);
900 realfile = old;
901 }
902 }
903 }
904
905 return realfile;
906}
907
908static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
909 int datasync)
910{
911 struct file *realfile;
912 int err;
913
914 err = ovl_sync_status(ofs: OVL_FS(sb: file_inode(f: file)->i_sb));
915 if (err <= 0)
916 return err;
917
918 realfile = ovl_dir_real_file(file, want_upper: true);
919 err = PTR_ERR_OR_ZERO(ptr: realfile);
920
921 /* Nothing to sync for lower */
922 if (!realfile || err)
923 return err;
924
925 return vfs_fsync_range(file: realfile, start, end, datasync);
926}
927
928static int ovl_dir_release(struct inode *inode, struct file *file)
929{
930 struct ovl_dir_file *od = file->private_data;
931
932 if (od->cache) {
933 inode_lock(inode);
934 ovl_cache_put(od, inode);
935 inode_unlock(inode);
936 }
937 fput(od->realfile);
938 if (od->upperfile)
939 fput(od->upperfile);
940 kfree(objp: od);
941
942 return 0;
943}
944
945static int ovl_dir_open(struct inode *inode, struct file *file)
946{
947 struct path realpath;
948 struct file *realfile;
949 struct ovl_dir_file *od;
950 enum ovl_path_type type;
951
952 od = kzalloc(size: sizeof(struct ovl_dir_file), GFP_KERNEL);
953 if (!od)
954 return -ENOMEM;
955
956 type = ovl_path_real(dentry: file->f_path.dentry, path: &realpath);
957 realfile = ovl_dir_open_realfile(file, realpath: &realpath);
958 if (IS_ERR(ptr: realfile)) {
959 kfree(objp: od);
960 return PTR_ERR(ptr: realfile);
961 }
962 od->realfile = realfile;
963 od->is_real = ovl_dir_is_real(dir: inode);
964 od->is_upper = OVL_TYPE_UPPER(type);
965 file->private_data = od;
966
967 return 0;
968}
969
970WRAP_DIR_ITER(ovl_iterate) // FIXME!
971const struct file_operations ovl_dir_operations = {
972 .read = generic_read_dir,
973 .open = ovl_dir_open,
974 .iterate_shared = shared_ovl_iterate,
975 .llseek = ovl_dir_llseek,
976 .fsync = ovl_dir_fsync,
977 .release = ovl_dir_release,
978};
979
980int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
981{
982 int err;
983 struct ovl_cache_entry *p, *n;
984 struct rb_root root = RB_ROOT;
985 const struct cred *old_cred;
986
987 old_cred = ovl_override_creds(sb: dentry->d_sb);
988 err = ovl_dir_read_merged(dentry, list, root: &root);
989 revert_creds(old_cred);
990 if (err)
991 return err;
992
993 err = 0;
994
995 list_for_each_entry_safe(p, n, list, l_node) {
996 /*
997 * Select whiteouts in upperdir, they should
998 * be cleared when deleting this directory.
999 */
1000 if (p->is_whiteout) {
1001 if (p->is_upper)
1002 continue;
1003 goto del_entry;
1004 }
1005
1006 if (p->name[0] == '.') {
1007 if (p->len == 1)
1008 goto del_entry;
1009 if (p->len == 2 && p->name[1] == '.')
1010 goto del_entry;
1011 }
1012 err = -ENOTEMPTY;
1013 break;
1014
1015del_entry:
1016 list_del(entry: &p->l_node);
1017 kfree(objp: p);
1018 }
1019
1020 return err;
1021}
1022
1023void ovl_cleanup_whiteouts(struct ovl_fs *ofs, struct dentry *upper,
1024 struct list_head *list)
1025{
1026 struct ovl_cache_entry *p;
1027
1028 inode_lock_nested(inode: upper->d_inode, subclass: I_MUTEX_CHILD);
1029 list_for_each_entry(p, list, l_node) {
1030 struct dentry *dentry;
1031
1032 if (WARN_ON(!p->is_whiteout || !p->is_upper))
1033 continue;
1034
1035 dentry = ovl_lookup_upper(ofs, name: p->name, base: upper, len: p->len);
1036 if (IS_ERR(ptr: dentry)) {
1037 pr_err("lookup '%s/%.*s' failed (%i)\n",
1038 upper->d_name.name, p->len, p->name,
1039 (int) PTR_ERR(dentry));
1040 continue;
1041 }
1042 if (dentry->d_inode)
1043 ovl_cleanup(ofs, dir: upper->d_inode, dentry);
1044 dput(dentry);
1045 }
1046 inode_unlock(inode: upper->d_inode);
1047}
1048
1049static bool ovl_check_d_type(struct dir_context *ctx, const char *name,
1050 int namelen, loff_t offset, u64 ino,
1051 unsigned int d_type)
1052{
1053 struct ovl_readdir_data *rdd =
1054 container_of(ctx, struct ovl_readdir_data, ctx);
1055
1056 /* Even if d_type is not supported, DT_DIR is returned for . and .. */
1057 if (!strncmp(name, ".", namelen) || !strncmp(name, "..", namelen))
1058 return true;
1059
1060 if (d_type != DT_UNKNOWN)
1061 rdd->d_type_supported = true;
1062
1063 return true;
1064}
1065
1066/*
1067 * Returns 1 if d_type is supported, 0 not supported/unknown. Negative values
1068 * if error is encountered.
1069 */
1070int ovl_check_d_type_supported(const struct path *realpath)
1071{
1072 int err;
1073 struct ovl_readdir_data rdd = {
1074 .ctx.actor = ovl_check_d_type,
1075 .d_type_supported = false,
1076 };
1077
1078 err = ovl_dir_read(realpath, rdd: &rdd);
1079 if (err)
1080 return err;
1081
1082 return rdd.d_type_supported;
1083}
1084
1085#define OVL_INCOMPATDIR_NAME "incompat"
1086
1087static int ovl_workdir_cleanup_recurse(struct ovl_fs *ofs, const struct path *path,
1088 int level)
1089{
1090 int err;
1091 struct inode *dir = path->dentry->d_inode;
1092 LIST_HEAD(list);
1093 struct ovl_cache_entry *p;
1094 struct ovl_readdir_data rdd = {
1095 .ctx.actor = ovl_fill_plain,
1096 .list = &list,
1097 };
1098 bool incompat = false;
1099
1100 /*
1101 * The "work/incompat" directory is treated specially - if it is not
1102 * empty, instead of printing a generic error and mounting read-only,
1103 * we will error about incompat features and fail the mount.
1104 *
1105 * When called from ovl_indexdir_cleanup(), path->dentry->d_name.name
1106 * starts with '#'.
1107 */
1108 if (level == 2 &&
1109 !strcmp(path->dentry->d_name.name, OVL_INCOMPATDIR_NAME))
1110 incompat = true;
1111
1112 err = ovl_dir_read(realpath: path, rdd: &rdd);
1113 if (err)
1114 goto out;
1115
1116 inode_lock_nested(inode: dir, subclass: I_MUTEX_PARENT);
1117 list_for_each_entry(p, &list, l_node) {
1118 struct dentry *dentry;
1119
1120 if (p->name[0] == '.') {
1121 if (p->len == 1)
1122 continue;
1123 if (p->len == 2 && p->name[1] == '.')
1124 continue;
1125 } else if (incompat) {
1126 pr_err("overlay with incompat feature '%s' cannot be mounted\n",
1127 p->name);
1128 err = -EINVAL;
1129 break;
1130 }
1131 dentry = ovl_lookup_upper(ofs, name: p->name, base: path->dentry, len: p->len);
1132 if (IS_ERR(ptr: dentry))
1133 continue;
1134 if (dentry->d_inode)
1135 err = ovl_workdir_cleanup(ofs, dir, mnt: path->mnt, dentry, level);
1136 dput(dentry);
1137 if (err)
1138 break;
1139 }
1140 inode_unlock(inode: dir);
1141out:
1142 ovl_cache_free(list: &list);
1143 return err;
1144}
1145
1146int ovl_workdir_cleanup(struct ovl_fs *ofs, struct inode *dir,
1147 struct vfsmount *mnt, struct dentry *dentry, int level)
1148{
1149 int err;
1150
1151 if (!d_is_dir(dentry) || level > 1) {
1152 return ovl_cleanup(ofs, dir, dentry);
1153 }
1154
1155 err = ovl_do_rmdir(ofs, dir, dentry);
1156 if (err) {
1157 struct path path = { .mnt = mnt, .dentry = dentry };
1158
1159 inode_unlock(inode: dir);
1160 err = ovl_workdir_cleanup_recurse(ofs, path: &path, level: level + 1);
1161 inode_lock_nested(inode: dir, subclass: I_MUTEX_PARENT);
1162 if (!err)
1163 err = ovl_cleanup(ofs, dir, dentry);
1164 }
1165
1166 return err;
1167}
1168
1169int ovl_indexdir_cleanup(struct ovl_fs *ofs)
1170{
1171 int err;
1172 struct dentry *indexdir = ofs->indexdir;
1173 struct dentry *index = NULL;
1174 struct inode *dir = indexdir->d_inode;
1175 struct path path = { .mnt = ovl_upper_mnt(ofs), .dentry = indexdir };
1176 LIST_HEAD(list);
1177 struct ovl_cache_entry *p;
1178 struct ovl_readdir_data rdd = {
1179 .ctx.actor = ovl_fill_plain,
1180 .list = &list,
1181 };
1182
1183 err = ovl_dir_read(realpath: &path, rdd: &rdd);
1184 if (err)
1185 goto out;
1186
1187 inode_lock_nested(inode: dir, subclass: I_MUTEX_PARENT);
1188 list_for_each_entry(p, &list, l_node) {
1189 if (p->name[0] == '.') {
1190 if (p->len == 1)
1191 continue;
1192 if (p->len == 2 && p->name[1] == '.')
1193 continue;
1194 }
1195 index = ovl_lookup_upper(ofs, name: p->name, base: indexdir, len: p->len);
1196 if (IS_ERR(ptr: index)) {
1197 err = PTR_ERR(ptr: index);
1198 index = NULL;
1199 break;
1200 }
1201 /* Cleanup leftover from index create/cleanup attempt */
1202 if (index->d_name.name[0] == '#') {
1203 err = ovl_workdir_cleanup(ofs, dir, mnt: path.mnt, dentry: index, level: 1);
1204 if (err)
1205 break;
1206 goto next;
1207 }
1208 err = ovl_verify_index(ofs, index);
1209 if (!err) {
1210 goto next;
1211 } else if (err == -ESTALE) {
1212 /* Cleanup stale index entries */
1213 err = ovl_cleanup(ofs, dir, dentry: index);
1214 } else if (err != -ENOENT) {
1215 /*
1216 * Abort mount to avoid corrupting the index if
1217 * an incompatible index entry was found or on out
1218 * of memory.
1219 */
1220 break;
1221 } else if (ofs->config.nfs_export) {
1222 /*
1223 * Whiteout orphan index to block future open by
1224 * handle after overlay nlink dropped to zero.
1225 */
1226 err = ovl_cleanup_and_whiteout(ofs, dir, dentry: index);
1227 } else {
1228 /* Cleanup orphan index entries */
1229 err = ovl_cleanup(ofs, dir, dentry: index);
1230 }
1231
1232 if (err)
1233 break;
1234
1235next:
1236 dput(index);
1237 index = NULL;
1238 }
1239 dput(index);
1240 inode_unlock(inode: dir);
1241out:
1242 ovl_cache_free(list: &list);
1243 if (err)
1244 pr_err("failed index dir cleanup (%i)\n", err);
1245 return err;
1246}
1247

source code of linux/fs/overlayfs/readdir.c