1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2011 Novell Inc.
4 * Copyright (C) 2016 Red Hat, Inc.
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"
17 struct ovl_lookup_data {
18 struct super_block *sb;
28 static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
29 size_t prelen, const char *post)
33 struct ovl_fs *ofs = OVL_FS(d->sb);
35 buf = ovl_get_redirect_xattr(ofs, dentry, prelen + strlen(post));
36 if (IS_ERR_OR_NULL(buf))
41 * One of the ancestor path elements in an absolute path
42 * lookup in ovl_lookup_layer() could have been opaque and
43 * that will stop further lookup in lower layers (d->stop=true)
44 * But we have found an absolute redirect in decendant path
45 * element and that should force continue lookup in lower
46 * layers (reset d->stop).
50 res = strlen(buf) + 1;
51 memmove(buf + prelen, buf, res);
52 memcpy(buf, d->name.name, prelen);
58 d->name.name = d->redirect;
59 d->name.len = strlen(d->redirect);
64 static int ovl_acceptable(void *ctx, struct dentry *dentry)
67 * A non-dir origin may be disconnected, which is fine, because
68 * we only need it for its unique inode number.
70 if (!d_is_dir(dentry))
73 /* Don't decode a deleted empty directory */
74 if (d_unhashed(dentry))
77 /* Check if directory belongs to the layer we are decoding from */
78 return is_subdir(dentry, ((struct vfsmount *)ctx)->mnt_root);
82 * Check validity of an overlay file handle buffer.
84 * Return 0 for a valid file handle.
85 * Return -ENODATA for "origin unknown".
86 * Return <0 for an invalid file handle.
88 int ovl_check_fb_len(struct ovl_fb *fb, int fb_len)
90 if (fb_len < sizeof(struct ovl_fb) || fb_len < fb->len)
93 if (fb->magic != OVL_FH_MAGIC)
96 /* Treat larger version and unknown flags as "origin unknown" */
97 if (fb->version > OVL_FH_VERSION || fb->flags & ~OVL_FH_FLAG_ALL)
100 /* Treat endianness mismatch as "origin unknown" */
101 if (!(fb->flags & OVL_FH_FLAG_ANY_ENDIAN) &&
102 (fb->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)
108 static struct ovl_fh *ovl_get_fh(struct ovl_fs *ofs, struct dentry *dentry,
112 struct ovl_fh *fh = NULL;
114 res = ovl_do_getxattr(ofs, dentry, ox, NULL, 0);
116 if (res == -ENODATA || res == -EOPNOTSUPP)
120 /* Zero size value means "copied up but origin unknown" */
124 fh = kzalloc(res + OVL_FH_WIRE_OFFSET, GFP_KERNEL);
126 return ERR_PTR(-ENOMEM);
128 res = ovl_do_getxattr(ofs, dentry, ox, fh->buf, res);
132 err = ovl_check_fb_len(&fh->fb, res);
146 pr_warn_ratelimited("failed to get origin (%i)\n", res);
149 pr_warn_ratelimited("invalid origin (%*phN)\n", res, fh);
153 struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
154 struct vfsmount *mnt, bool connected)
159 if (!capable(CAP_DAC_READ_SEARCH))
163 * Make sure that the stored uuid matches the uuid of the lower
164 * layer where file handle will be decoded.
165 * In case of uuid=off option just make sure that stored uuid is null.
167 if (ofs->config.uuid ? !uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid) :
168 !uuid_is_null(&fh->fb.uuid))
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);
177 * Treat stale file handle to lower file as "origin unknown".
178 * upper file handle could become stale when upper file is
179 * unlinked and this information is needed to handle stale
180 * index entries correctly.
182 if (real == ERR_PTR(-ESTALE) &&
183 !(fh->fb.flags & OVL_FH_FLAG_PATH_UPPER))
188 if (ovl_dentry_weird(real)) {
196 static bool ovl_is_opaquedir(struct super_block *sb, struct dentry *dentry)
198 return ovl_check_dir_xattr(sb, dentry, OVL_XATTR_OPAQUE);
201 static struct dentry *ovl_lookup_positive_unlocked(const char *name,
202 struct dentry *base, int len,
205 struct dentry *ret = lookup_one_len_unlocked(name, base, len);
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 /* Recheck condition under lock */
211 if (d_is_negative(ret) && ret->d_lockref.count == 1)
213 spin_unlock(&ret->d_lock);
216 ret = ERR_PTR(-ENOENT);
221 static 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)
228 bool last_element = !post[0];
230 this = ovl_lookup_positive_unlocked(name, base, namelen, drop_negative);
234 if (err == -ENOENT || err == -ENAMETOOLONG)
239 if (ovl_dentry_weird(this)) {
240 /* Don't support traversing automounts and other weirdness */
244 if (ovl_is_whiteout(this)) {
245 d->stop = d->opaque = true;
249 * This dentry should be a regular file if previous layer lookup
250 * found a metacopy dentry.
252 if (last_element && d->metacopy && !d_is_reg(this)) {
256 if (!d_can_lookup(this)) {
257 if (d->is_dir || !last_element) {
261 err = ovl_check_metacopy_xattr(OVL_FS(d->sb), this);
266 d->stop = !d->metacopy;
267 if (!d->metacopy || d->last)
270 if (ovl_lookup_trap_inode(d->sb, this)) {
271 /* Caught in a trap of overlapping layers */
281 if (ovl_is_opaquedir(d->sb, this)) {
288 err = ovl_check_redirect(this, d, prelen, post);
305 static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
306 struct dentry **ret, bool drop_negative)
308 /* Counting down from the end, since the prefix can change */
309 size_t rem = d->name.len - 1;
310 struct dentry *dentry = NULL;
313 if (d->name.name[0] != '/')
314 return ovl_lookup_single(base, d, d->name.name, d->name.len,
315 0, "", ret, drop_negative);
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;
323 /* Verify we did not go off the rails */
324 if (WARN_ON(s[-1] != '/'))
327 err = ovl_lookup_single(base, d, s, thislen,
328 d->name.len - rem, next, &base,
339 if (WARN_ON(rem >= d->name.len))
347 int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
348 struct dentry *upperdentry, struct ovl_path **stackp)
350 struct dentry *origin = NULL;
353 for (i = 1; i < ofs->numlayer; i++) {
355 * If lower fs uuid is not unique among lower fs we cannot match
358 if (ofs->layers[i].fsid &&
359 ofs->layers[i].fs->bad_uuid)
362 origin = ovl_decode_real_fh(ofs, fh, ofs->layers[i].mnt,
370 else if (IS_ERR(origin))
371 return PTR_ERR(origin);
373 if (upperdentry && !ovl_is_whiteout(upperdentry) &&
374 inode_wrong_type(d_inode(upperdentry), d_inode(origin)->i_mode))
378 *stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL);
383 **stackp = (struct ovl_path){
385 .layer = &ofs->layers[i]
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);
398 static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry,
399 struct ovl_path **stackp)
401 struct ovl_fh *fh = ovl_get_fh(ofs, upperdentry, OVL_XATTR_ORIGIN);
404 if (IS_ERR_OR_NULL(fh))
407 err = ovl_check_origin_fh(ofs, fh, false, upperdentry, stackp);
420 * Verify that @fh matches the file handle stored in xattr @name.
421 * Return 0 on match, -ESTALE on mismatch, < 0 on error.
423 static int ovl_verify_fh(struct ovl_fs *ofs, struct dentry *dentry,
424 enum ovl_xattr ox, const struct ovl_fh *fh)
426 struct ovl_fh *ofh = ovl_get_fh(ofs, dentry, ox);
435 if (fh->fb.len != ofh->fb.len || memcmp(&fh->fb, &ofh->fb, fh->fb.len))
443 * Verify that @real dentry matches the file handle stored in xattr @name.
445 * If @set is true and there is no stored file handle, encode @real and store
446 * file handle in xattr @name.
448 * Return 0 on match, -ESTALE on mismatch, -ENODATA on no xattr, < 0 on error.
450 int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
451 enum ovl_xattr ox, struct dentry *real, bool is_upper,
458 fh = ovl_encode_real_fh(ofs, real, is_upper);
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);
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);
483 /* Get upper dentry from index */
484 struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index)
487 struct dentry *upper;
489 if (!d_is_dir(index))
492 fh = ovl_get_fh(ofs, index, OVL_XATTR_UPPER);
493 if (IS_ERR_OR_NULL(fh))
496 upper = ovl_decode_real_fh(ofs, fh, ovl_upper_mnt(ofs), true);
499 if (IS_ERR_OR_NULL(upper))
500 return upper ?: ERR_PTR(-ESTALE);
502 if (!d_is_dir(upper)) {
503 pr_warn_ratelimited("invalid index upper (%pd2, upper=%pd2).\n",
506 return ERR_PTR(-EIO);
513 * Verify that an index entry name matches the origin file handle stored in
514 * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path.
515 * Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error.
517 int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index)
519 struct ovl_fh *fh = NULL;
521 struct ovl_path origin = { };
522 struct ovl_path *stack = &origin;
523 struct dentry *upper = NULL;
530 if (index->d_name.len < sizeof(struct ovl_fb)*2)
534 len = index->d_name.len / 2;
535 fh = kzalloc(len + OVL_FH_WIRE_OFFSET, GFP_KERNEL);
540 if (hex2bin(fh->buf, index->d_name.name, len))
543 err = ovl_check_fb_len(&fh->fb, len);
548 * Whiteout index entries are used as an indication that an exported
549 * overlay file handle should be treated as stale (i.e. after unlink
550 * of the overlay inode). These entries contain no origin xattr.
552 if (ovl_is_whiteout(index))
556 * Verifying directory index entries are not stale is expensive, so
557 * only verify stale dir index if NFS export is enabled.
559 if (d_is_dir(index) && !ofs->config.nfs_export)
563 * Directory index entries should have 'upper' xattr pointing to the
564 * real upper dir. Non-dir index entries are hardlinks to the upper
565 * real inode. For non-dir index, we can read the copy up origin xattr
566 * directly from the index dentry, but for dir index we first need to
567 * decode the upper directory.
569 upper = ovl_index_upper(ofs, index);
570 if (IS_ERR_OR_NULL(upper)) {
571 err = PTR_ERR(upper);
573 * Directory index entries with no 'upper' xattr need to be
574 * removed. When dir index entry has a stale 'upper' xattr,
575 * we assume that upper dir was removed and we treat the dir
576 * index as orphan entry that needs to be whited out.
585 err = ovl_verify_fh(ofs, upper, OVL_XATTR_ORIGIN, fh);
590 /* Check if non-dir index is orphan and don't warn before cleaning it */
591 if (!d_is_dir(index) && d_inode(index)->i_nlink == 1) {
592 err = ovl_check_origin_fh(ofs, fh, false, index, &stack);
596 if (ovl_get_nlink(ofs, origin.dentry, index, 0) == 0)
606 pr_warn_ratelimited("failed to verify index (%pd2, ftype=%x, err=%i)\n",
607 index, d_inode(index)->i_mode & S_IFMT, err);
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);
618 static int ovl_get_index_name_fh(struct ovl_fh *fh, struct qstr *name)
622 n = kcalloc(fh->fb.len, 2, GFP_KERNEL);
626 s = bin2hex(n, fh->buf, fh->fb.len);
627 *name = (struct qstr) QSTR_INIT(n, s - n);
634 * Lookup in indexdir for the index entry of a lower real inode or a copy up
635 * origin inode. The index entry name is the hex representation of the lower
638 * If the index dentry in negative, then either no lower aliases have been
639 * copied up yet, or aliases have been copied up in older kernels and are
642 * If the index dentry for a copy up origin inode is positive, but points
643 * to an inode different than the upper inode, then either the upper inode
644 * has been copied up and not indexed or it was indexed, but since then
645 * index dir was cleared. Either way, that index cannot be used to indentify
648 int ovl_get_index_name(struct ovl_fs *ofs, struct dentry *origin,
654 fh = ovl_encode_real_fh(ofs, origin, false);
658 err = ovl_get_index_name_fh(fh, name);
664 /* Lookup index by file handle for NFS export */
665 struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
667 struct dentry *index;
671 err = ovl_get_index_name_fh(fh, &name);
675 index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
678 if (PTR_ERR(index) == -ENOENT)
683 if (ovl_is_whiteout(index))
685 else if (ovl_dentry_weird(index))
694 struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
695 struct dentry *origin, bool verify)
697 struct dentry *index;
700 bool is_dir = d_is_dir(origin);
703 err = ovl_get_index_name(ofs, origin, &name);
707 index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
709 err = PTR_ERR(index);
710 if (err == -ENOENT) {
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,
721 inode = d_inode(index);
722 if (ovl_is_whiteout(index) && !verify) {
724 * When index lookup is called with !verify for decoding an
725 * overlay file handle, a whiteout index implies that decode
726 * should treat file handle as stale and no need to print a
730 index = ERR_PTR(-ESTALE);
732 } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
733 inode_wrong_type(inode, d_inode(origin)->i_mode)) {
735 * Index should always be of the same file type as origin
736 * except for the case of a whiteout index. A whiteout
737 * index should only exist if all lower aliases have been
738 * unlinked, which means that finding a lower origin on lookup
739 * whose index is a whiteout should be treated as an error.
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);
745 } else if (is_dir && verify) {
747 pr_warn_ratelimited("suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n",
752 /* Verify that dir index 'upper' xattr points to upper dir */
753 err = ovl_verify_upper(ofs, index, upper, false);
755 if (err == -ESTALE) {
756 pr_warn_ratelimited("suspected multiply redirected dir found (upper=%pd2, origin=%pd2, index=%pd2).\n",
757 upper, origin, index);
761 } else if (upper && d_inode(upper) != inode) {
775 index = ERR_PTR(-EIO);
780 * Returns next layer in stack starting from top.
781 * Returns -1 if this is the last layer.
783 int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
785 struct ovl_entry *oe = dentry->d_fsdata;
789 ovl_path_upper(dentry, path);
791 return oe->numlower ? 1 : -1;
794 BUG_ON(idx > oe->numlower);
795 path->dentry = oe->lowerstack[idx - 1].dentry;
796 path->mnt = oe->lowerstack[idx - 1].layer->mnt;
798 return (idx < oe->numlower) ? idx + 1 : -1;
801 /* Fix missing 'origin' xattr */
802 static int ovl_fix_origin(struct ovl_fs *ofs, struct dentry *dentry,
803 struct dentry *lower, struct dentry *upper)
807 if (ovl_check_origin_xattr(ofs, upper))
810 err = ovl_want_write(dentry);
814 err = ovl_set_origin(ofs, lower, upper);
816 err = ovl_set_impure(dentry->d_parent, upper->d_parent);
818 ovl_drop_write(dentry);
822 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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;
841 bool uppermetacopy = false;
842 struct ovl_lookup_data d = {
844 .name = dentry->d_name,
848 .last = ofs->config.redirect_follow ? false : !poe->numlower,
853 if (dentry->d_name.len > ofs->namelen)
854 return ERR_PTR(-ENAMETOOLONG);
856 old_cred = ovl_override_creds(dentry->d_sb);
857 upperdir = ovl_dentry_upper(dentry->d_parent);
859 err = ovl_lookup_layer(upperdir, &d, &upperdentry, true);
863 if (upperdentry && upperdentry->d_flags & DCACHE_OP_REAL) {
868 if (upperdentry && !d.is_dir) {
870 * Lookup copy up origin by decoding origin file handle.
871 * We may get a disconnected dentry, which is fine,
872 * because we only need to hold the origin inode in
873 * cache and use its inode number. We may even get a
874 * connected dentry, that is not under any of the lower
875 * layers root. That is also fine for using it's inode
876 * number - it's the same as if we held a reference
877 * to a dentry in lower layer that was moved under us.
879 err = ovl_check_origin(ofs, upperdentry, &origin_path);
884 uppermetacopy = true;
889 upperredirect = kstrdup(d.redirect, GFP_KERNEL);
892 if (d.redirect[0] == '/')
895 upperopaque = d.opaque;
898 if (!d.stop && poe->numlower) {
900 stack = kcalloc(ofs->numlayer - 1, sizeof(struct ovl_path),
906 for (i = 0; !d.stop && i < poe->numlower; i++) {
907 struct ovl_path lower = poe->lowerstack[i];
909 if (!ofs->config.redirect_follow)
910 d.last = i == poe->numlower - 1;
912 d.last = lower.layer->idx == roe->numlower;
914 err = ovl_lookup_layer(lower.dentry, &d, &this, false);
921 if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) {
924 pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry);
929 * If no origin fh is stored in upper of a merge dir, store fh
930 * of lower dir and set upper parent "impure".
932 if (upperdentry && !ctr && !ofs->noxattr && d.is_dir) {
933 err = ovl_fix_origin(ofs, dentry, this, upperdentry);
941 * When "verify_lower" feature is enabled, do not merge with a
942 * lower dir that does not match a stored origin xattr. In any
943 * case, only verified origin is used for index lookup.
945 * For non-dir dentry, if index=on, then ensure origin
946 * matches the dentry found using path based lookup,
947 * otherwise error out.
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);
962 if (d.metacopy && ctr) {
964 * Do not store intermediate metacopy dentries in
965 * lower chain, except top most lower metacopy dentry.
966 * Continue the loop so that if there is an absolute
967 * redirect on this dentry, poe can be reset to roe.
972 stack[ctr].dentry = this;
973 stack[ctr].layer = lower.layer;
978 * Following redirects can have security consequences: it's like
979 * a symlink into the lower layer without the permission checks.
980 * This is only a problem if the upper layer is untrusted (e.g
981 * comes from an USB drive). This can allow a non-readable file
982 * or directory to become readable.
984 * Only following redirects when redirects are enabled disables
985 * this attack vector when not necessary.
988 if (d.redirect && !ofs->config.redirect_follow) {
989 pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n",
997 if (d.redirect && d.redirect[0] == '/' && poe != roe) {
999 /* Find the current layer on the root dentry */
1000 i = lower.layer->idx - 1;
1005 * For regular non-metacopy upper dentries, there is no lower
1006 * path based lookup, hence ctr will be zero. If a dentry is found
1007 * using ORIGIN xattr on upper, install it in stack.
1009 * For metacopy dentry, path based lookup will find lower dentries.
1010 * Just make sure a corresponding data dentry has been found.
1012 if (d.metacopy || (uppermetacopy && !ctr)) {
1013 pr_warn_ratelimited("metacopy with no lower data found - abort lookup (%pd2)\n",
1017 } else if (!d.is_dir && upperdentry && !ctr && origin_path) {
1018 if (WARN_ON(stack != NULL)) {
1022 stack = origin_path;
1024 origin = origin_path->dentry;
1029 * Always lookup index if there is no-upperdentry.
1031 * For the case of upperdentry, we have set origin by now if it
1032 * needed to be set. There are basically three cases.
1034 * For directories, lookup index by lower inode and verify it matches
1035 * upper inode. We only trust dir index if we verified that lower dir
1036 * matches origin, otherwise dir index entries may be inconsistent
1037 * and we ignore them.
1039 * For regular upper, we already set origin if upper had ORIGIN
1040 * xattr. There is no verification though as there is no path
1041 * based dentry lookup in lower in this case.
1043 * For metacopy upper, we set a verified origin already if index
1044 * is enabled and if upper had an ORIGIN xattr.
1047 if (!upperdentry && ctr)
1048 origin = stack[0].dentry;
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);
1060 oe = ovl_alloc_entry(ctr);
1065 memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr);
1066 dentry->d_fsdata = oe;
1069 ovl_dentry_set_opaque(dentry);
1072 ovl_dentry_set_upper_alias(dentry);
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;
1081 err = ovl_check_metacopy_xattr(ofs, upperdentry);
1084 uppermetacopy = err;
1087 if (upperdentry || ctr) {
1088 struct ovl_inode_params oip = {
1089 .upperdentry = upperdentry,
1093 .redirect = upperredirect,
1094 .lowerdata = (ctr > 1 && !d.is_dir) ?
1095 stack[ctr - 1].dentry : NULL,
1098 inode = ovl_get_inode(dentry->d_sb, &oip);
1099 err = PTR_ERR(inode);
1102 if (upperdentry && !uppermetacopy)
1103 ovl_set_flag(OVL_UPPERDATA, inode);
1106 ovl_dentry_update_reval(dentry, upperdentry,
1107 DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
1109 revert_creds(old_cred);
1111 dput(origin_path->dentry);
1117 return d_splice_alias(inode, dentry);
1120 dentry->d_fsdata = NULL;
1124 for (i = 0; i < ctr; i++)
1125 dput(stack[i].dentry);
1129 dput(origin_path->dentry);
1133 kfree(upperredirect);
1136 revert_creds(old_cred);
1137 return ERR_PTR(err);
1140 bool ovl_lower_positive(struct dentry *dentry)
1142 struct ovl_entry *poe = dentry->d_parent->d_fsdata;
1143 const struct qstr *name = &dentry->d_name;
1144 const struct cred *old_cred;
1146 bool positive = false;
1150 * If dentry is negative, then lower is positive iff this is a
1153 if (!dentry->d_inode)
1154 return ovl_dentry_is_opaque(dentry);
1156 /* Negative upper -> positive lower */
1157 if (!ovl_dentry_upper(dentry))
1160 old_cred = ovl_override_creds(dentry->d_sb);
1161 /* Positive upper -> have to look up lower to see whether it exists */
1162 for (i = 0; !done && !positive && i < poe->numlower; i++) {
1163 struct dentry *this;
1164 struct dentry *lowerdir = poe->lowerstack[i].dentry;
1166 this = lookup_positive_unlocked(name->name, lowerdir,
1169 switch (PTR_ERR(this)) {
1176 * Assume something is there, we just couldn't
1183 positive = !ovl_is_whiteout(this);
1188 revert_creds(old_cred);