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TOMOYO Linux Cross Reference
Linux/fs/overlayfs/readdir.c

Version: ~ [ linux-5.0-rc6 ] ~ [ linux-4.20.10 ] ~ [ linux-4.19.23 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.101 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.158 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.174 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.134 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.63 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

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

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