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6
7#include <linux/fs.h>
8#include <linux/cred.h>
9#include <linux/ctype.h>
10#include <linux/namei.h>
11#include <linux/xattr.h>
12#include <linux/ratelimit.h>
13#include <linux/mount.h>
14#include <linux/exportfs.h>
15#include "overlayfs.h"
16
17struct ovl_lookup_data {
18 struct super_block *sb;
19 struct qstr name;
20 bool is_dir;
21 bool opaque;
22 bool stop;
23 bool last;
24 char *redirect;
25 bool metacopy;
26};
27
28static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
29 size_t prelen, const char *post)
30{
31 int res;
32 char *buf;
33 struct ovl_fs *ofs = OVL_FS(d->sb);
34
35 buf = ovl_get_redirect_xattr(ofs, dentry, prelen + strlen(post));
36 if (IS_ERR_OR_NULL(buf))
37 return PTR_ERR(buf);
38
39 if (buf[0] == '/') {
40
41
42
43
44
45
46
47
48 d->stop = false;
49 } else {
50 res = strlen(buf) + 1;
51 memmove(buf + prelen, buf, res);
52 memcpy(buf, d->name.name, prelen);
53 }
54
55 strcat(buf, post);
56 kfree(d->redirect);
57 d->redirect = buf;
58 d->name.name = d->redirect;
59 d->name.len = strlen(d->redirect);
60
61 return 0;
62}
63
64static int ovl_acceptable(void *ctx, struct dentry *dentry)
65{
66
67
68
69
70 if (!d_is_dir(dentry))
71 return 1;
72
73
74 if (d_unhashed(dentry))
75 return 0;
76
77
78 return is_subdir(dentry, ((struct vfsmount *)ctx)->mnt_root);
79}
80
81
82
83
84
85
86
87
88int ovl_check_fb_len(struct ovl_fb *fb, int fb_len)
89{
90 if (fb_len < sizeof(struct ovl_fb) || fb_len < fb->len)
91 return -EINVAL;
92
93 if (fb->magic != OVL_FH_MAGIC)
94 return -EINVAL;
95
96
97 if (fb->version > OVL_FH_VERSION || fb->flags & ~OVL_FH_FLAG_ALL)
98 return -ENODATA;
99
100
101 if (!(fb->flags & OVL_FH_FLAG_ANY_ENDIAN) &&
102 (fb->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)
103 return -ENODATA;
104
105 return 0;
106}
107
108static struct ovl_fh *ovl_get_fh(struct ovl_fs *ofs, struct dentry *dentry,
109 enum ovl_xattr ox)
110{
111 int res, err;
112 struct ovl_fh *fh = NULL;
113
114 res = ovl_do_getxattr(ofs, dentry, ox, NULL, 0);
115 if (res < 0) {
116 if (res == -ENODATA || res == -EOPNOTSUPP)
117 return NULL;
118 goto fail;
119 }
120
121 if (res == 0)
122 return NULL;
123
124 fh = kzalloc(res + OVL_FH_WIRE_OFFSET, GFP_KERNEL);
125 if (!fh)
126 return ERR_PTR(-ENOMEM);
127
128 res = ovl_do_getxattr(ofs, dentry, ox, fh->buf, res);
129 if (res < 0)
130 goto fail;
131
132 err = ovl_check_fb_len(&fh->fb, res);
133 if (err < 0) {
134 if (err == -ENODATA)
135 goto out;
136 goto invalid;
137 }
138
139 return fh;
140
141out:
142 kfree(fh);
143 return NULL;
144
145fail:
146 pr_warn_ratelimited("failed to get origin (%i)\n", res);
147 goto out;
148invalid:
149 pr_warn_ratelimited("invalid origin (%*phN)\n", res, fh);
150 goto out;
151}
152
153struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
154 struct vfsmount *mnt, bool connected)
155{
156 struct dentry *real;
157 int bytes;
158
159 if (!capable(CAP_DAC_READ_SEARCH))
160 return NULL;
161
162
163
164
165
166
167 if (ofs->config.uuid ? !uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid) :
168 !uuid_is_null(&fh->fb.uuid))
169 return NULL;
170
171 bytes = (fh->fb.len - offsetof(struct ovl_fb, fid));
172 real = exportfs_decode_fh(mnt, (struct fid *)fh->fb.fid,
173 bytes >> 2, (int)fh->fb.type,
174 connected ? ovl_acceptable : NULL, mnt);
175 if (IS_ERR(real)) {
176
177
178
179
180
181
182 if (real == ERR_PTR(-ESTALE) &&
183 !(fh->fb.flags & OVL_FH_FLAG_PATH_UPPER))
184 real = NULL;
185 return real;
186 }
187
188 if (ovl_dentry_weird(real)) {
189 dput(real);
190 return NULL;
191 }
192
193 return real;
194}
195
196static bool ovl_is_opaquedir(struct super_block *sb, struct dentry *dentry)
197{
198 return ovl_check_dir_xattr(sb, dentry, OVL_XATTR_OPAQUE);
199}
200
201static struct dentry *ovl_lookup_positive_unlocked(const char *name,
202 struct dentry *base, int len,
203 bool drop_negative)
204{
205 struct dentry *ret = lookup_one_len_unlocked(name, base, len);
206
207 if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
208 if (drop_negative && ret->d_lockref.count == 1) {
209 spin_lock(&ret->d_lock);
210
211 if (d_is_negative(ret) && ret->d_lockref.count == 1)
212 __d_drop(ret);
213 spin_unlock(&ret->d_lock);
214 }
215 dput(ret);
216 ret = ERR_PTR(-ENOENT);
217 }
218 return ret;
219}
220
221static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
222 const char *name, unsigned int namelen,
223 size_t prelen, const char *post,
224 struct dentry **ret, bool drop_negative)
225{
226 struct dentry *this;
227 int err;
228 bool last_element = !post[0];
229
230 this = ovl_lookup_positive_unlocked(name, base, namelen, drop_negative);
231 if (IS_ERR(this)) {
232 err = PTR_ERR(this);
233 this = NULL;
234 if (err == -ENOENT || err == -ENAMETOOLONG)
235 goto out;
236 goto out_err;
237 }
238
239 if (ovl_dentry_weird(this)) {
240
241 err = -EREMOTE;
242 goto out_err;
243 }
244 if (ovl_is_whiteout(this)) {
245 d->stop = d->opaque = true;
246 goto put_and_out;
247 }
248
249
250
251
252 if (last_element && d->metacopy && !d_is_reg(this)) {
253 d->stop = true;
254 goto put_and_out;
255 }
256 if (!d_can_lookup(this)) {
257 if (d->is_dir || !last_element) {
258 d->stop = true;
259 goto put_and_out;
260 }
261 err = ovl_check_metacopy_xattr(OVL_FS(d->sb), this);
262 if (err < 0)
263 goto out_err;
264
265 d->metacopy = err;
266 d->stop = !d->metacopy;
267 if (!d->metacopy || d->last)
268 goto out;
269 } else {
270 if (ovl_lookup_trap_inode(d->sb, this)) {
271
272 err = -ELOOP;
273 goto out_err;
274 }
275
276 if (last_element)
277 d->is_dir = true;
278 if (d->last)
279 goto out;
280
281 if (ovl_is_opaquedir(d->sb, this)) {
282 d->stop = true;
283 if (last_element)
284 d->opaque = true;
285 goto out;
286 }
287 }
288 err = ovl_check_redirect(this, d, prelen, post);
289 if (err)
290 goto out_err;
291out:
292 *ret = this;
293 return 0;
294
295put_and_out:
296 dput(this);
297 this = NULL;
298 goto out;
299
300out_err:
301 dput(this);
302 return err;
303}
304
305static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
306 struct dentry **ret, bool drop_negative)
307{
308
309 size_t rem = d->name.len - 1;
310 struct dentry *dentry = NULL;
311 int err;
312
313 if (d->name.name[0] != '/')
314 return ovl_lookup_single(base, d, d->name.name, d->name.len,
315 0, "", ret, drop_negative);
316
317 while (!IS_ERR_OR_NULL(base) && d_can_lookup(base)) {
318 const char *s = d->name.name + d->name.len - rem;
319 const char *next = strchrnul(s, '/');
320 size_t thislen = next - s;
321 bool end = !next[0];
322
323
324 if (WARN_ON(s[-1] != '/'))
325 return -EIO;
326
327 err = ovl_lookup_single(base, d, s, thislen,
328 d->name.len - rem, next, &base,
329 drop_negative);
330 dput(dentry);
331 if (err)
332 return err;
333 dentry = base;
334 if (end)
335 break;
336
337 rem -= thislen + 1;
338
339 if (WARN_ON(rem >= d->name.len))
340 return -EIO;
341 }
342 *ret = dentry;
343 return 0;
344}
345
346
347int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
348 struct dentry *upperdentry, struct ovl_path **stackp)
349{
350 struct dentry *origin = NULL;
351 int i;
352
353 for (i = 1; i < ofs->numlayer; i++) {
354
355
356
357
358 if (ofs->layers[i].fsid &&
359 ofs->layers[i].fs->bad_uuid)
360 continue;
361
362 origin = ovl_decode_real_fh(ofs, fh, ofs->layers[i].mnt,
363 connected);
364 if (origin)
365 break;
366 }
367
368 if (!origin)
369 return -ESTALE;
370 else if (IS_ERR(origin))
371 return PTR_ERR(origin);
372
373 if (upperdentry && !ovl_is_whiteout(upperdentry) &&
374 inode_wrong_type(d_inode(upperdentry), d_inode(origin)->i_mode))
375 goto invalid;
376
377 if (!*stackp)
378 *stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL);
379 if (!*stackp) {
380 dput(origin);
381 return -ENOMEM;
382 }
383 **stackp = (struct ovl_path){
384 .dentry = origin,
385 .layer = &ofs->layers[i]
386 };
387
388 return 0;
389
390invalid:
391 pr_warn_ratelimited("invalid origin (%pd2, ftype=%x, origin ftype=%x).\n",
392 upperdentry, d_inode(upperdentry)->i_mode & S_IFMT,
393 d_inode(origin)->i_mode & S_IFMT);
394 dput(origin);
395 return -EIO;
396}
397
398static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry,
399 struct ovl_path **stackp)
400{
401 struct ovl_fh *fh = ovl_get_fh(ofs, upperdentry, OVL_XATTR_ORIGIN);
402 int err;
403
404 if (IS_ERR_OR_NULL(fh))
405 return PTR_ERR(fh);
406
407 err = ovl_check_origin_fh(ofs, fh, false, upperdentry, stackp);
408 kfree(fh);
409
410 if (err) {
411 if (err == -ESTALE)
412 return 0;
413 return err;
414 }
415
416 return 0;
417}
418
419
420
421
422
423static int ovl_verify_fh(struct ovl_fs *ofs, struct dentry *dentry,
424 enum ovl_xattr ox, const struct ovl_fh *fh)
425{
426 struct ovl_fh *ofh = ovl_get_fh(ofs, dentry, ox);
427 int err = 0;
428
429 if (!ofh)
430 return -ENODATA;
431
432 if (IS_ERR(ofh))
433 return PTR_ERR(ofh);
434
435 if (fh->fb.len != ofh->fb.len || memcmp(&fh->fb, &ofh->fb, fh->fb.len))
436 err = -ESTALE;
437
438 kfree(ofh);
439 return err;
440}
441
442
443
444
445
446
447
448
449
450int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
451 enum ovl_xattr ox, struct dentry *real, bool is_upper,
452 bool set)
453{
454 struct inode *inode;
455 struct ovl_fh *fh;
456 int err;
457
458 fh = ovl_encode_real_fh(ofs, real, is_upper);
459 err = PTR_ERR(fh);
460 if (IS_ERR(fh)) {
461 fh = NULL;
462 goto fail;
463 }
464
465 err = ovl_verify_fh(ofs, dentry, ox, fh);
466 if (set && err == -ENODATA)
467 err = ovl_do_setxattr(ofs, dentry, ox, fh->buf, fh->fb.len);
468 if (err)
469 goto fail;
470
471out:
472 kfree(fh);
473 return err;
474
475fail:
476 inode = d_inode(real);
477 pr_warn_ratelimited("failed to verify %s (%pd2, ino=%lu, err=%i)\n",
478 is_upper ? "upper" : "origin", real,
479 inode ? inode->i_ino : 0, err);
480 goto out;
481}
482
483
484struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index)
485{
486 struct ovl_fh *fh;
487 struct dentry *upper;
488
489 if (!d_is_dir(index))
490 return dget(index);
491
492 fh = ovl_get_fh(ofs, index, OVL_XATTR_UPPER);
493 if (IS_ERR_OR_NULL(fh))
494 return ERR_CAST(fh);
495
496 upper = ovl_decode_real_fh(ofs, fh, ovl_upper_mnt(ofs), true);
497 kfree(fh);
498
499 if (IS_ERR_OR_NULL(upper))
500 return upper ?: ERR_PTR(-ESTALE);
501
502 if (!d_is_dir(upper)) {
503 pr_warn_ratelimited("invalid index upper (%pd2, upper=%pd2).\n",
504 index, upper);
505 dput(upper);
506 return ERR_PTR(-EIO);
507 }
508
509 return upper;
510}
511
512
513
514
515
516
517int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index)
518{
519 struct ovl_fh *fh = NULL;
520 size_t len;
521 struct ovl_path origin = { };
522 struct ovl_path *stack = &origin;
523 struct dentry *upper = NULL;
524 int err;
525
526 if (!d_inode(index))
527 return 0;
528
529 err = -EINVAL;
530 if (index->d_name.len < sizeof(struct ovl_fb)*2)
531 goto fail;
532
533 err = -ENOMEM;
534 len = index->d_name.len / 2;
535 fh = kzalloc(len + OVL_FH_WIRE_OFFSET, GFP_KERNEL);
536 if (!fh)
537 goto fail;
538
539 err = -EINVAL;
540 if (hex2bin(fh->buf, index->d_name.name, len))
541 goto fail;
542
543 err = ovl_check_fb_len(&fh->fb, len);
544 if (err)
545 goto fail;
546
547
548
549
550
551
552 if (ovl_is_whiteout(index))
553 goto out;
554
555
556
557
558
559 if (d_is_dir(index) && !ofs->config.nfs_export)
560 goto out;
561
562
563
564
565
566
567
568
569 upper = ovl_index_upper(ofs, index);
570 if (IS_ERR_OR_NULL(upper)) {
571 err = PTR_ERR(upper);
572
573
574
575
576
577
578 if (err == -ESTALE)
579 goto orphan;
580 else if (!err)
581 err = -ESTALE;
582 goto fail;
583 }
584
585 err = ovl_verify_fh(ofs, upper, OVL_XATTR_ORIGIN, fh);
586 dput(upper);
587 if (err)
588 goto fail;
589
590
591 if (!d_is_dir(index) && d_inode(index)->i_nlink == 1) {
592 err = ovl_check_origin_fh(ofs, fh, false, index, &stack);
593 if (err)
594 goto fail;
595
596 if (ovl_get_nlink(ofs, origin.dentry, index, 0) == 0)
597 goto orphan;
598 }
599
600out:
601 dput(origin.dentry);
602 kfree(fh);
603 return err;
604
605fail:
606 pr_warn_ratelimited("failed to verify index (%pd2, ftype=%x, err=%i)\n",
607 index, d_inode(index)->i_mode & S_IFMT, err);
608 goto out;
609
610orphan:
611 pr_warn_ratelimited("orphan index entry (%pd2, ftype=%x, nlink=%u)\n",
612 index, d_inode(index)->i_mode & S_IFMT,
613 d_inode(index)->i_nlink);
614 err = -ENOENT;
615 goto out;
616}
617
618static int ovl_get_index_name_fh(struct ovl_fh *fh, struct qstr *name)
619{
620 char *n, *s;
621
622 n = kcalloc(fh->fb.len, 2, GFP_KERNEL);
623 if (!n)
624 return -ENOMEM;
625
626 s = bin2hex(n, fh->buf, fh->fb.len);
627 *name = (struct qstr) QSTR_INIT(n, s - n);
628
629 return 0;
630
631}
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648int ovl_get_index_name(struct ovl_fs *ofs, struct dentry *origin,
649 struct qstr *name)
650{
651 struct ovl_fh *fh;
652 int err;
653
654 fh = ovl_encode_real_fh(ofs, origin, false);
655 if (IS_ERR(fh))
656 return PTR_ERR(fh);
657
658 err = ovl_get_index_name_fh(fh, name);
659
660 kfree(fh);
661 return err;
662}
663
664
665struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
666{
667 struct dentry *index;
668 struct qstr name;
669 int err;
670
671 err = ovl_get_index_name_fh(fh, &name);
672 if (err)
673 return ERR_PTR(err);
674
675 index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
676 kfree(name.name);
677 if (IS_ERR(index)) {
678 if (PTR_ERR(index) == -ENOENT)
679 index = NULL;
680 return index;
681 }
682
683 if (ovl_is_whiteout(index))
684 err = -ESTALE;
685 else if (ovl_dentry_weird(index))
686 err = -EIO;
687 else
688 return index;
689
690 dput(index);
691 return ERR_PTR(err);
692}
693
694struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
695 struct dentry *origin, bool verify)
696{
697 struct dentry *index;
698 struct inode *inode;
699 struct qstr name;
700 bool is_dir = d_is_dir(origin);
701 int err;
702
703 err = ovl_get_index_name(ofs, origin, &name);
704 if (err)
705 return ERR_PTR(err);
706
707 index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
708 if (IS_ERR(index)) {
709 err = PTR_ERR(index);
710 if (err == -ENOENT) {
711 index = NULL;
712 goto out;
713 }
714 pr_warn_ratelimited("failed inode index lookup (ino=%lu, key=%.*s, err=%i);\n"
715 "overlayfs: mount with '-o index=off' to disable inodes index.\n",
716 d_inode(origin)->i_ino, name.len, name.name,
717 err);
718 goto out;
719 }
720
721 inode = d_inode(index);
722 if (ovl_is_whiteout(index) && !verify) {
723
724
725
726
727
728
729 dput(index);
730 index = ERR_PTR(-ESTALE);
731 goto out;
732 } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
733 inode_wrong_type(inode, d_inode(origin)->i_mode)) {
734
735
736
737
738
739
740
741 pr_warn_ratelimited("bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n",
742 index, d_inode(index)->i_mode & S_IFMT,
743 d_inode(origin)->i_mode & S_IFMT);
744 goto fail;
745 } else if (is_dir && verify) {
746 if (!upper) {
747 pr_warn_ratelimited("suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n",
748 origin, index);
749 goto fail;
750 }
751
752
753 err = ovl_verify_upper(ofs, index, upper, false);
754 if (err) {
755 if (err == -ESTALE) {
756 pr_warn_ratelimited("suspected multiply redirected dir found (upper=%pd2, origin=%pd2, index=%pd2).\n",
757 upper, origin, index);
758 }
759 goto fail;
760 }
761 } else if (upper && d_inode(upper) != inode) {
762 goto out_dput;
763 }
764out:
765 kfree(name.name);
766 return index;
767
768out_dput:
769 dput(index);
770 index = NULL;
771 goto out;
772
773fail:
774 dput(index);
775 index = ERR_PTR(-EIO);
776 goto out;
777}
778
779
780
781
782
783int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
784{
785 struct ovl_entry *oe = dentry->d_fsdata;
786
787 BUG_ON(idx < 0);
788 if (idx == 0) {
789 ovl_path_upper(dentry, path);
790 if (path->dentry)
791 return oe->numlower ? 1 : -1;
792 idx++;
793 }
794 BUG_ON(idx > oe->numlower);
795 path->dentry = oe->lowerstack[idx - 1].dentry;
796 path->mnt = oe->lowerstack[idx - 1].layer->mnt;
797
798 return (idx < oe->numlower) ? idx + 1 : -1;
799}
800
801
802static int ovl_fix_origin(struct ovl_fs *ofs, struct dentry *dentry,
803 struct dentry *lower, struct dentry *upper)
804{
805 int err;
806
807 if (ovl_check_origin_xattr(ofs, upper))
808 return 0;
809
810 err = ovl_want_write(dentry);
811 if (err)
812 return err;
813
814 err = ovl_set_origin(ofs, dentry, lower, upper);
815 if (!err)
816 err = ovl_set_impure(dentry->d_parent, upper->d_parent);
817
818 ovl_drop_write(dentry);
819 return err;
820}
821
822struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
823 unsigned int flags)
824{
825 struct ovl_entry *oe;
826 const struct cred *old_cred;
827 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
828 struct ovl_entry *poe = dentry->d_parent->d_fsdata;
829 struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;
830 struct ovl_path *stack = NULL, *origin_path = NULL;
831 struct dentry *upperdir, *upperdentry = NULL;
832 struct dentry *origin = NULL;
833 struct dentry *index = NULL;
834 unsigned int ctr = 0;
835 struct inode *inode = NULL;
836 bool upperopaque = false;
837 char *upperredirect = NULL;
838 struct dentry *this;
839 unsigned int i;
840 int err;
841 bool uppermetacopy = false;
842 struct ovl_lookup_data d = {
843 .sb = dentry->d_sb,
844 .name = dentry->d_name,
845 .is_dir = false,
846 .opaque = false,
847 .stop = false,
848 .last = ofs->config.redirect_follow ? false : !poe->numlower,
849 .redirect = NULL,
850 .metacopy = false,
851 };
852
853 if (dentry->d_name.len > ofs->namelen)
854 return ERR_PTR(-ENAMETOOLONG);
855
856 old_cred = ovl_override_creds(dentry->d_sb);
857 upperdir = ovl_dentry_upper(dentry->d_parent);
858 if (upperdir) {
859 err = ovl_lookup_layer(upperdir, &d, &upperdentry, true);
860 if (err)
861 goto out;
862
863 if (upperdentry && upperdentry->d_flags & DCACHE_OP_REAL) {
864 dput(upperdentry);
865 err = -EREMOTE;
866 goto out;
867 }
868 if (upperdentry && !d.is_dir) {
869
870
871
872
873
874
875
876
877
878
879 err = ovl_check_origin(ofs, upperdentry, &origin_path);
880 if (err)
881 goto out_put_upper;
882
883 if (d.metacopy)
884 uppermetacopy = true;
885 }
886
887 if (d.redirect) {
888 err = -ENOMEM;
889 upperredirect = kstrdup(d.redirect, GFP_KERNEL);
890 if (!upperredirect)
891 goto out_put_upper;
892 if (d.redirect[0] == '/')
893 poe = roe;
894 }
895 upperopaque = d.opaque;
896 }
897
898 if (!d.stop && poe->numlower) {
899 err = -ENOMEM;
900 stack = kcalloc(ofs->numlayer - 1, sizeof(struct ovl_path),
901 GFP_KERNEL);
902 if (!stack)
903 goto out_put_upper;
904 }
905
906 for (i = 0; !d.stop && i < poe->numlower; i++) {
907 struct ovl_path lower = poe->lowerstack[i];
908
909 if (!ofs->config.redirect_follow)
910 d.last = i == poe->numlower - 1;
911 else
912 d.last = lower.layer->idx == roe->numlower;
913
914 err = ovl_lookup_layer(lower.dentry, &d, &this, false);
915 if (err)
916 goto out_put;
917
918 if (!this)
919 continue;
920
921 if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) {
922 dput(this);
923 err = -EPERM;
924 pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry);
925 goto out_put;
926 }
927
928
929
930
931
932 if (upperdentry && !ctr && !ofs->noxattr && d.is_dir) {
933 err = ovl_fix_origin(ofs, dentry, this, upperdentry);
934 if (err) {
935 dput(this);
936 goto out_put;
937 }
938 }
939
940
941
942
943
944
945
946
947
948
949 if (upperdentry && !ctr &&
950 ((d.is_dir && ovl_verify_lower(dentry->d_sb)) ||
951 (!d.is_dir && ofs->config.index && origin_path))) {
952 err = ovl_verify_origin(ofs, upperdentry, this, false);
953 if (err) {
954 dput(this);
955 if (d.is_dir)
956 break;
957 goto out_put;
958 }
959 origin = this;
960 }
961
962 if (d.metacopy && ctr) {
963
964
965
966
967
968
969 dput(this);
970 this = NULL;
971 } else {
972 stack[ctr].dentry = this;
973 stack[ctr].layer = lower.layer;
974 ctr++;
975 }
976
977
978
979
980
981
982
983
984
985
986
987 err = -EPERM;
988 if (d.redirect && !ofs->config.redirect_follow) {
989 pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n",
990 dentry);
991 goto out_put;
992 }
993
994 if (d.stop)
995 break;
996
997 if (d.redirect && d.redirect[0] == '/' && poe != roe) {
998 poe = roe;
999
1000 i = lower.layer->idx - 1;
1001 }
1002 }
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012 if (d.metacopy || (uppermetacopy && !ctr)) {
1013 pr_warn_ratelimited("metacopy with no lower data found - abort lookup (%pd2)\n",
1014 dentry);
1015 err = -EIO;
1016 goto out_put;
1017 } else if (!d.is_dir && upperdentry && !ctr && origin_path) {
1018 if (WARN_ON(stack != NULL)) {
1019 err = -EIO;
1020 goto out_put;
1021 }
1022 stack = origin_path;
1023 ctr = 1;
1024 origin = origin_path->dentry;
1025 origin_path = NULL;
1026 }
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047 if (!upperdentry && ctr)
1048 origin = stack[0].dentry;
1049
1050 if (origin && ovl_indexdir(dentry->d_sb) &&
1051 (!d.is_dir || ovl_index_all(dentry->d_sb))) {
1052 index = ovl_lookup_index(ofs, upperdentry, origin, true);
1053 if (IS_ERR(index)) {
1054 err = PTR_ERR(index);
1055 index = NULL;
1056 goto out_put;
1057 }
1058 }
1059
1060 oe = ovl_alloc_entry(ctr);
1061 err = -ENOMEM;
1062 if (!oe)
1063 goto out_put;
1064
1065 memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr);
1066 dentry->d_fsdata = oe;
1067
1068 if (upperopaque)
1069 ovl_dentry_set_opaque(dentry);
1070
1071 if (upperdentry)
1072 ovl_dentry_set_upper_alias(dentry);
1073 else if (index) {
1074 upperdentry = dget(index);
1075 upperredirect = ovl_get_redirect_xattr(ofs, upperdentry, 0);
1076 if (IS_ERR(upperredirect)) {
1077 err = PTR_ERR(upperredirect);
1078 upperredirect = NULL;
1079 goto out_free_oe;
1080 }
1081 err = ovl_check_metacopy_xattr(ofs, upperdentry);
1082 if (err < 0)
1083 goto out_free_oe;
1084 uppermetacopy = err;
1085 }
1086
1087 if (upperdentry || ctr) {
1088 struct ovl_inode_params oip = {
1089 .upperdentry = upperdentry,
1090 .lowerpath = stack,
1091 .index = index,
1092 .numlower = ctr,
1093 .redirect = upperredirect,
1094 .lowerdata = (ctr > 1 && !d.is_dir) ?
1095 stack[ctr - 1].dentry : NULL,
1096 };
1097
1098 inode = ovl_get_inode(dentry->d_sb, &oip);
1099 err = PTR_ERR(inode);
1100 if (IS_ERR(inode))
1101 goto out_free_oe;
1102 if (upperdentry && !uppermetacopy)
1103 ovl_set_flag(OVL_UPPERDATA, inode);
1104 }
1105
1106 ovl_dentry_update_reval(dentry, upperdentry,
1107 DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
1108
1109 revert_creds(old_cred);
1110 if (origin_path) {
1111 dput(origin_path->dentry);
1112 kfree(origin_path);
1113 }
1114 dput(index);
1115 kfree(stack);
1116 kfree(d.redirect);
1117 return d_splice_alias(inode, dentry);
1118
1119out_free_oe:
1120 dentry->d_fsdata = NULL;
1121 kfree(oe);
1122out_put:
1123 dput(index);
1124 for (i = 0; i < ctr; i++)
1125 dput(stack[i].dentry);
1126 kfree(stack);
1127out_put_upper:
1128 if (origin_path) {
1129 dput(origin_path->dentry);
1130 kfree(origin_path);
1131 }
1132 dput(upperdentry);
1133 kfree(upperredirect);
1134out:
1135 kfree(d.redirect);
1136 revert_creds(old_cred);
1137 return ERR_PTR(err);
1138}
1139
1140bool ovl_lower_positive(struct dentry *dentry)
1141{
1142 struct ovl_entry *poe = dentry->d_parent->d_fsdata;
1143 const struct qstr *name = &dentry->d_name;
1144 const struct cred *old_cred;
1145 unsigned int i;
1146 bool positive = false;
1147 bool done = false;
1148
1149
1150
1151
1152
1153 if (!dentry->d_inode)
1154 return ovl_dentry_is_opaque(dentry);
1155
1156
1157 if (!ovl_dentry_upper(dentry))
1158 return true;
1159
1160 old_cred = ovl_override_creds(dentry->d_sb);
1161
1162 for (i = 0; !done && !positive && i < poe->numlower; i++) {
1163 struct dentry *this;
1164 struct dentry *lowerdir = poe->lowerstack[i].dentry;
1165
1166 this = lookup_positive_unlocked(name->name, lowerdir,
1167 name->len);
1168 if (IS_ERR(this)) {
1169 switch (PTR_ERR(this)) {
1170 case -ENOENT:
1171 case -ENAMETOOLONG:
1172 break;
1173
1174 default:
1175
1176
1177
1178
1179 positive = true;
1180 break;
1181 }
1182 } else {
1183 positive = !ovl_is_whiteout(this);
1184 done = true;
1185 dput(this);
1186 }
1187 }
1188 revert_creds(old_cred);
1189
1190 return positive;
1191}
1192