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)
34 buf = ovl_get_redirect_xattr(dentry, prelen + strlen(post));
35 if (IS_ERR_OR_NULL(buf))
40 * One of the ancestor path elements in an absolute path
41 * lookup in ovl_lookup_layer() could have been opaque and
42 * that will stop further lookup in lower layers (d->stop=true)
43 * But we have found an absolute redirect in decendant path
44 * element and that should force continue lookup in lower
45 * layers (reset d->stop).
49 res = strlen(buf) + 1;
50 memmove(buf + prelen, buf, res);
51 memcpy(buf, d->name.name, prelen);
57 d->name.name = d->redirect;
58 d->name.len = strlen(d->redirect);
63 static int ovl_acceptable(void *ctx, struct dentry *dentry)
66 * A non-dir origin may be disconnected, which is fine, because
67 * we only need it for its unique inode number.
69 if (!d_is_dir(dentry))
72 /* Don't decode a deleted empty directory */
73 if (d_unhashed(dentry))
76 /* Check if directory belongs to the layer we are decoding from */
77 return is_subdir(dentry, ((struct vfsmount *)ctx)->mnt_root);
81 * Check validity of an overlay file handle buffer.
83 * Return 0 for a valid file handle.
84 * Return -ENODATA for "origin unknown".
85 * Return <0 for an invalid file handle.
87 int ovl_check_fb_len(struct ovl_fb *fb, int fb_len)
89 if (fb_len < sizeof(struct ovl_fb) || fb_len < fb->len)
92 if (fb->magic != OVL_FH_MAGIC)
95 /* Treat larger version and unknown flags as "origin unknown" */
96 if (fb->version > OVL_FH_VERSION || fb->flags & ~OVL_FH_FLAG_ALL)
99 /* Treat endianness mismatch as "origin unknown" */
100 if (!(fb->flags & OVL_FH_FLAG_ANY_ENDIAN) &&
101 (fb->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)
107 static struct ovl_fh *ovl_get_fh(struct dentry *dentry, const char *name)
110 struct ovl_fh *fh = NULL;
112 res = vfs_getxattr(dentry, name, NULL, 0);
114 if (res == -ENODATA || res == -EOPNOTSUPP)
118 /* Zero size value means "copied up but origin unknown" */
122 fh = kzalloc(res + OVL_FH_WIRE_OFFSET, GFP_KERNEL);
124 return ERR_PTR(-ENOMEM);
126 res = vfs_getxattr(dentry, name, fh->buf, res);
130 err = ovl_check_fb_len(&fh->fb, res);
144 pr_warn_ratelimited("failed to get origin (%i)\n", res);
147 pr_warn_ratelimited("invalid origin (%*phN)\n", res, fh);
151 struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
158 * Make sure that the stored uuid matches the uuid of the lower
159 * layer where file handle will be decoded.
161 if (!uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid))
164 bytes = (fh->fb.len - offsetof(struct ovl_fb, fid));
165 real = exportfs_decode_fh(mnt, (struct fid *)fh->fb.fid,
166 bytes >> 2, (int)fh->fb.type,
167 connected ? ovl_acceptable : NULL, mnt);
170 * Treat stale file handle to lower file as "origin unknown".
171 * upper file handle could become stale when upper file is
172 * unlinked and this information is needed to handle stale
173 * index entries correctly.
175 if (real == ERR_PTR(-ESTALE) &&
176 !(fh->fb.flags & OVL_FH_FLAG_PATH_UPPER))
181 if (ovl_dentry_weird(real)) {
189 static bool ovl_is_opaquedir(struct dentry *dentry)
191 return ovl_check_dir_xattr(dentry, OVL_XATTR_OPAQUE);
194 static struct dentry *ovl_lookup_positive_unlocked(const char *name,
195 struct dentry *base, int len,
198 struct dentry *ret = lookup_one_len_unlocked(name, base, len);
200 if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
201 if (drop_negative && ret->d_lockref.count == 1) {
202 spin_lock(&ret->d_lock);
203 /* Recheck condition under lock */
204 if (d_is_negative(ret) && ret->d_lockref.count == 1)
206 spin_unlock(&ret->d_lock);
209 ret = ERR_PTR(-ENOENT);
214 static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
215 const char *name, unsigned int namelen,
216 size_t prelen, const char *post,
217 struct dentry **ret, bool drop_negative)
221 bool last_element = !post[0];
223 this = ovl_lookup_positive_unlocked(name, base, namelen, drop_negative);
227 if (err == -ENOENT || err == -ENAMETOOLONG)
232 if (ovl_dentry_weird(this)) {
233 /* Don't support traversing automounts and other weirdness */
237 if (ovl_is_whiteout(this)) {
238 d->stop = d->opaque = true;
242 * This dentry should be a regular file if previous layer lookup
243 * found a metacopy dentry.
245 if (last_element && d->metacopy && !d_is_reg(this)) {
249 if (!d_can_lookup(this)) {
250 if (d->is_dir || !last_element) {
254 err = ovl_check_metacopy_xattr(this);
259 d->stop = !d->metacopy;
260 if (!d->metacopy || d->last)
263 if (ovl_lookup_trap_inode(d->sb, this)) {
264 /* Caught in a trap of overlapping layers */
274 if (ovl_is_opaquedir(this)) {
281 err = ovl_check_redirect(this, d, prelen, post);
298 static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
299 struct dentry **ret, bool drop_negative)
301 /* Counting down from the end, since the prefix can change */
302 size_t rem = d->name.len - 1;
303 struct dentry *dentry = NULL;
306 if (d->name.name[0] != '/')
307 return ovl_lookup_single(base, d, d->name.name, d->name.len,
308 0, "", ret, drop_negative);
310 while (!IS_ERR_OR_NULL(base) && d_can_lookup(base)) {
311 const char *s = d->name.name + d->name.len - rem;
312 const char *next = strchrnul(s, '/');
313 size_t thislen = next - s;
316 /* Verify we did not go off the rails */
317 if (WARN_ON(s[-1] != '/'))
320 err = ovl_lookup_single(base, d, s, thislen,
321 d->name.len - rem, next, &base,
332 if (WARN_ON(rem >= d->name.len))
340 int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
341 struct dentry *upperdentry, struct ovl_path **stackp)
343 struct dentry *origin = NULL;
346 for (i = 1; i < ofs->numlayer; i++) {
348 * If lower fs uuid is not unique among lower fs we cannot match
351 if (ofs->layers[i].fsid &&
352 ofs->layers[i].fs->bad_uuid)
355 origin = ovl_decode_real_fh(fh, ofs->layers[i].mnt,
363 else if (IS_ERR(origin))
364 return PTR_ERR(origin);
366 if (upperdentry && !ovl_is_whiteout(upperdentry) &&
367 ((d_inode(origin)->i_mode ^ d_inode(upperdentry)->i_mode) & S_IFMT))
371 *stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL);
376 **stackp = (struct ovl_path){
378 .layer = &ofs->layers[i]
384 pr_warn_ratelimited("invalid origin (%pd2, ftype=%x, origin ftype=%x).\n",
385 upperdentry, d_inode(upperdentry)->i_mode & S_IFMT,
386 d_inode(origin)->i_mode & S_IFMT);
391 static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry,
392 struct ovl_path **stackp, unsigned int *ctrp)
394 struct ovl_fh *fh = ovl_get_fh(upperdentry, OVL_XATTR_ORIGIN);
397 if (IS_ERR_OR_NULL(fh))
400 err = ovl_check_origin_fh(ofs, fh, false, upperdentry, stackp);
417 * Verify that @fh matches the file handle stored in xattr @name.
418 * Return 0 on match, -ESTALE on mismatch, < 0 on error.
420 static int ovl_verify_fh(struct dentry *dentry, const char *name,
421 const struct ovl_fh *fh)
423 struct ovl_fh *ofh = ovl_get_fh(dentry, name);
432 if (fh->fb.len != ofh->fb.len || memcmp(&fh->fb, &ofh->fb, fh->fb.len))
440 * Verify that @real dentry matches the file handle stored in xattr @name.
442 * If @set is true and there is no stored file handle, encode @real and store
443 * file handle in xattr @name.
445 * Return 0 on match, -ESTALE on mismatch, -ENODATA on no xattr, < 0 on error.
447 int ovl_verify_set_fh(struct dentry *dentry, const char *name,
448 struct dentry *real, bool is_upper, bool set)
454 fh = ovl_encode_real_fh(real, is_upper);
461 err = ovl_verify_fh(dentry, name, fh);
462 if (set && err == -ENODATA)
463 err = ovl_do_setxattr(dentry, name, fh->buf, fh->fb.len, 0);
472 inode = d_inode(real);
473 pr_warn_ratelimited("failed to verify %s (%pd2, ino=%lu, err=%i)\n",
474 is_upper ? "upper" : "origin", real,
475 inode ? inode->i_ino : 0, err);
479 /* Get upper dentry from index */
480 struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index)
483 struct dentry *upper;
485 if (!d_is_dir(index))
488 fh = ovl_get_fh(index, OVL_XATTR_UPPER);
489 if (IS_ERR_OR_NULL(fh))
492 upper = ovl_decode_real_fh(fh, ovl_upper_mnt(ofs), true);
495 if (IS_ERR_OR_NULL(upper))
496 return upper ?: ERR_PTR(-ESTALE);
498 if (!d_is_dir(upper)) {
499 pr_warn_ratelimited("invalid index upper (%pd2, upper=%pd2).\n",
502 return ERR_PTR(-EIO);
509 * Verify that an index entry name matches the origin file handle stored in
510 * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path.
511 * Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error.
513 int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index)
515 struct ovl_fh *fh = NULL;
517 struct ovl_path origin = { };
518 struct ovl_path *stack = &origin;
519 struct dentry *upper = NULL;
526 if (index->d_name.len < sizeof(struct ovl_fb)*2)
530 len = index->d_name.len / 2;
531 fh = kzalloc(len + OVL_FH_WIRE_OFFSET, GFP_KERNEL);
536 if (hex2bin(fh->buf, index->d_name.name, len))
539 err = ovl_check_fb_len(&fh->fb, len);
544 * Whiteout index entries are used as an indication that an exported
545 * overlay file handle should be treated as stale (i.e. after unlink
546 * of the overlay inode). These entries contain no origin xattr.
548 if (ovl_is_whiteout(index))
552 * Verifying directory index entries are not stale is expensive, so
553 * only verify stale dir index if NFS export is enabled.
555 if (d_is_dir(index) && !ofs->config.nfs_export)
559 * Directory index entries should have 'upper' xattr pointing to the
560 * real upper dir. Non-dir index entries are hardlinks to the upper
561 * real inode. For non-dir index, we can read the copy up origin xattr
562 * directly from the index dentry, but for dir index we first need to
563 * decode the upper directory.
565 upper = ovl_index_upper(ofs, index);
566 if (IS_ERR_OR_NULL(upper)) {
567 err = PTR_ERR(upper);
569 * Directory index entries with no 'upper' xattr need to be
570 * removed. When dir index entry has a stale 'upper' xattr,
571 * we assume that upper dir was removed and we treat the dir
572 * index as orphan entry that needs to be whited out.
581 err = ovl_verify_fh(upper, OVL_XATTR_ORIGIN, fh);
586 /* Check if non-dir index is orphan and don't warn before cleaning it */
587 if (!d_is_dir(index) && d_inode(index)->i_nlink == 1) {
588 err = ovl_check_origin_fh(ofs, fh, false, index, &stack);
592 if (ovl_get_nlink(origin.dentry, index, 0) == 0)
602 pr_warn_ratelimited("failed to verify index (%pd2, ftype=%x, err=%i)\n",
603 index, d_inode(index)->i_mode & S_IFMT, err);
607 pr_warn_ratelimited("orphan index entry (%pd2, ftype=%x, nlink=%u)\n",
608 index, d_inode(index)->i_mode & S_IFMT,
609 d_inode(index)->i_nlink);
614 static int ovl_get_index_name_fh(struct ovl_fh *fh, struct qstr *name)
618 n = kcalloc(fh->fb.len, 2, GFP_KERNEL);
622 s = bin2hex(n, fh->buf, fh->fb.len);
623 *name = (struct qstr) QSTR_INIT(n, s - n);
630 * Lookup in indexdir for the index entry of a lower real inode or a copy up
631 * origin inode. The index entry name is the hex representation of the lower
634 * If the index dentry in negative, then either no lower aliases have been
635 * copied up yet, or aliases have been copied up in older kernels and are
638 * If the index dentry for a copy up origin inode is positive, but points
639 * to an inode different than the upper inode, then either the upper inode
640 * has been copied up and not indexed or it was indexed, but since then
641 * index dir was cleared. Either way, that index cannot be used to indentify
644 int ovl_get_index_name(struct dentry *origin, struct qstr *name)
649 fh = ovl_encode_real_fh(origin, false);
653 err = ovl_get_index_name_fh(fh, name);
659 /* Lookup index by file handle for NFS export */
660 struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
662 struct dentry *index;
666 err = ovl_get_index_name_fh(fh, &name);
670 index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
673 if (PTR_ERR(index) == -ENOENT)
678 if (ovl_is_whiteout(index))
680 else if (ovl_dentry_weird(index))
689 struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
690 struct dentry *origin, bool verify)
692 struct dentry *index;
695 bool is_dir = d_is_dir(origin);
698 err = ovl_get_index_name(origin, &name);
702 index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
704 err = PTR_ERR(index);
705 if (err == -ENOENT) {
709 pr_warn_ratelimited("failed inode index lookup (ino=%lu, key=%.*s, err=%i);\n"
710 "overlayfs: mount with '-o index=off' to disable inodes index.\n",
711 d_inode(origin)->i_ino, name.len, name.name,
716 inode = d_inode(index);
717 if (ovl_is_whiteout(index) && !verify) {
719 * When index lookup is called with !verify for decoding an
720 * overlay file handle, a whiteout index implies that decode
721 * should treat file handle as stale and no need to print a
725 index = ERR_PTR(-ESTALE);
727 } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
728 ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) {
730 * Index should always be of the same file type as origin
731 * except for the case of a whiteout index. A whiteout
732 * index should only exist if all lower aliases have been
733 * unlinked, which means that finding a lower origin on lookup
734 * whose index is a whiteout should be treated as an error.
736 pr_warn_ratelimited("bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n",
737 index, d_inode(index)->i_mode & S_IFMT,
738 d_inode(origin)->i_mode & S_IFMT);
740 } else if (is_dir && verify) {
742 pr_warn_ratelimited("suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n",
747 /* Verify that dir index 'upper' xattr points to upper dir */
748 err = ovl_verify_upper(index, upper, false);
750 if (err == -ESTALE) {
751 pr_warn_ratelimited("suspected multiply redirected dir found (upper=%pd2, origin=%pd2, index=%pd2).\n",
752 upper, origin, index);
756 } else if (upper && d_inode(upper) != inode) {
770 index = ERR_PTR(-EIO);
775 * Returns next layer in stack starting from top.
776 * Returns -1 if this is the last layer.
778 int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
780 struct ovl_entry *oe = dentry->d_fsdata;
784 ovl_path_upper(dentry, path);
786 return oe->numlower ? 1 : -1;
789 BUG_ON(idx > oe->numlower);
790 path->dentry = oe->lowerstack[idx - 1].dentry;
791 path->mnt = oe->lowerstack[idx - 1].layer->mnt;
793 return (idx < oe->numlower) ? idx + 1 : -1;
796 /* Fix missing 'origin' xattr */
797 static int ovl_fix_origin(struct dentry *dentry, struct dentry *lower,
798 struct dentry *upper)
802 if (ovl_check_origin_xattr(upper))
805 err = ovl_want_write(dentry);
809 err = ovl_set_origin(dentry, lower, upper);
811 err = ovl_set_impure(dentry->d_parent, upper->d_parent);
813 ovl_drop_write(dentry);
817 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
820 struct ovl_entry *oe;
821 const struct cred *old_cred;
822 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
823 struct ovl_entry *poe = dentry->d_parent->d_fsdata;
824 struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;
825 struct ovl_path *stack = NULL, *origin_path = NULL;
826 struct dentry *upperdir, *upperdentry = NULL;
827 struct dentry *origin = NULL;
828 struct dentry *index = NULL;
829 unsigned int ctr = 0;
830 struct inode *inode = NULL;
831 bool upperopaque = false;
832 char *upperredirect = NULL;
836 bool uppermetacopy = false;
837 struct ovl_lookup_data d = {
839 .name = dentry->d_name,
843 .last = ofs->config.redirect_follow ? false : !poe->numlower,
848 if (dentry->d_name.len > ofs->namelen)
849 return ERR_PTR(-ENAMETOOLONG);
851 old_cred = ovl_override_creds(dentry->d_sb);
852 upperdir = ovl_dentry_upper(dentry->d_parent);
854 err = ovl_lookup_layer(upperdir, &d, &upperdentry, true);
858 if (upperdentry && upperdentry->d_flags & DCACHE_OP_REAL) {
863 if (upperdentry && !d.is_dir) {
864 unsigned int origin_ctr = 0;
867 * Lookup copy up origin by decoding origin file handle.
868 * We may get a disconnected dentry, which is fine,
869 * because we only need to hold the origin inode in
870 * cache and use its inode number. We may even get a
871 * connected dentry, that is not under any of the lower
872 * layers root. That is also fine for using it's inode
873 * number - it's the same as if we held a reference
874 * to a dentry in lower layer that was moved under us.
876 err = ovl_check_origin(ofs, upperdentry, &origin_path,
882 uppermetacopy = true;
887 upperredirect = kstrdup(d.redirect, GFP_KERNEL);
890 if (d.redirect[0] == '/')
893 upperopaque = d.opaque;
896 if (!d.stop && poe->numlower) {
898 stack = kcalloc(ofs->numlayer - 1, sizeof(struct ovl_path),
904 for (i = 0; !d.stop && i < poe->numlower; i++) {
905 struct ovl_path lower = poe->lowerstack[i];
907 if (!ofs->config.redirect_follow)
908 d.last = i == poe->numlower - 1;
910 d.last = lower.layer->idx == roe->numlower;
912 err = ovl_lookup_layer(lower.dentry, &d, &this, false);
919 if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) {
921 pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry);
926 * If no origin fh is stored in upper of a merge dir, store fh
927 * of lower dir and set upper parent "impure".
929 if (upperdentry && !ctr && !ofs->noxattr && d.is_dir) {
930 err = ovl_fix_origin(dentry, this, upperdentry);
938 * When "verify_lower" feature is enabled, do not merge with a
939 * lower dir that does not match a stored origin xattr. In any
940 * case, only verified origin is used for index lookup.
942 * For non-dir dentry, if index=on, then ensure origin
943 * matches the dentry found using path based lookup,
944 * otherwise error out.
946 if (upperdentry && !ctr &&
947 ((d.is_dir && ovl_verify_lower(dentry->d_sb)) ||
948 (!d.is_dir && ofs->config.index && origin_path))) {
949 err = ovl_verify_origin(upperdentry, this, false);
959 if (d.metacopy && ctr) {
961 * Do not store intermediate metacopy dentries in
962 * lower chain, except top most lower metacopy dentry.
963 * Continue the loop so that if there is an absolute
964 * redirect on this dentry, poe can be reset to roe.
969 stack[ctr].dentry = this;
970 stack[ctr].layer = lower.layer;
975 * Following redirects can have security consequences: it's like
976 * a symlink into the lower layer without the permission checks.
977 * This is only a problem if the upper layer is untrusted (e.g
978 * comes from an USB drive). This can allow a non-readable file
979 * or directory to become readable.
981 * Only following redirects when redirects are enabled disables
982 * this attack vector when not necessary.
985 if (d.redirect && !ofs->config.redirect_follow) {
986 pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n",
994 if (d.redirect && d.redirect[0] == '/' && poe != roe) {
996 /* Find the current layer on the root dentry */
997 i = lower.layer->idx - 1;
1002 * For regular non-metacopy upper dentries, there is no lower
1003 * path based lookup, hence ctr will be zero. If a dentry is found
1004 * using ORIGIN xattr on upper, install it in stack.
1006 * For metacopy dentry, path based lookup will find lower dentries.
1007 * Just make sure a corresponding data dentry has been found.
1009 if (d.metacopy || (uppermetacopy && !ctr)) {
1012 } else if (!d.is_dir && upperdentry && !ctr && origin_path) {
1013 if (WARN_ON(stack != NULL)) {
1017 stack = origin_path;
1019 origin = origin_path->dentry;
1024 * Always lookup index if there is no-upperdentry.
1026 * For the case of upperdentry, we have set origin by now if it
1027 * needed to be set. There are basically three cases.
1029 * For directories, lookup index by lower inode and verify it matches
1030 * upper inode. We only trust dir index if we verified that lower dir
1031 * matches origin, otherwise dir index entries may be inconsistent
1032 * and we ignore them.
1034 * For regular upper, we already set origin if upper had ORIGIN
1035 * xattr. There is no verification though as there is no path
1036 * based dentry lookup in lower in this case.
1038 * For metacopy upper, we set a verified origin already if index
1039 * is enabled and if upper had an ORIGIN xattr.
1042 if (!upperdentry && ctr)
1043 origin = stack[0].dentry;
1045 if (origin && ovl_indexdir(dentry->d_sb) &&
1046 (!d.is_dir || ovl_index_all(dentry->d_sb))) {
1047 index = ovl_lookup_index(ofs, upperdentry, origin, true);
1048 if (IS_ERR(index)) {
1049 err = PTR_ERR(index);
1055 oe = ovl_alloc_entry(ctr);
1060 memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr);
1061 dentry->d_fsdata = oe;
1064 ovl_dentry_set_opaque(dentry);
1067 ovl_dentry_set_upper_alias(dentry);
1069 upperdentry = dget(index);
1070 upperredirect = ovl_get_redirect_xattr(upperdentry, 0);
1071 if (IS_ERR(upperredirect)) {
1072 err = PTR_ERR(upperredirect);
1073 upperredirect = NULL;
1078 if (upperdentry || ctr) {
1079 struct ovl_inode_params oip = {
1080 .upperdentry = upperdentry,
1084 .redirect = upperredirect,
1085 .lowerdata = (ctr > 1 && !d.is_dir) ?
1086 stack[ctr - 1].dentry : NULL,
1089 inode = ovl_get_inode(dentry->d_sb, &oip);
1090 err = PTR_ERR(inode);
1093 if (upperdentry && !uppermetacopy)
1094 ovl_set_flag(OVL_UPPERDATA, inode);
1097 ovl_dentry_update_reval(dentry, upperdentry,
1098 DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
1100 revert_creds(old_cred);
1102 dput(origin_path->dentry);
1108 return d_splice_alias(inode, dentry);
1111 dentry->d_fsdata = NULL;
1115 for (i = 0; i < ctr; i++)
1116 dput(stack[i].dentry);
1120 dput(origin_path->dentry);
1124 kfree(upperredirect);
1127 revert_creds(old_cred);
1128 return ERR_PTR(err);
1131 bool ovl_lower_positive(struct dentry *dentry)
1133 struct ovl_entry *poe = dentry->d_parent->d_fsdata;
1134 const struct qstr *name = &dentry->d_name;
1135 const struct cred *old_cred;
1137 bool positive = false;
1141 * If dentry is negative, then lower is positive iff this is a
1144 if (!dentry->d_inode)
1145 return ovl_dentry_is_opaque(dentry);
1147 /* Negative upper -> positive lower */
1148 if (!ovl_dentry_upper(dentry))
1151 old_cred = ovl_override_creds(dentry->d_sb);
1152 /* Positive upper -> have to look up lower to see whether it exists */
1153 for (i = 0; !done && !positive && i < poe->numlower; i++) {
1154 struct dentry *this;
1155 struct dentry *lowerdir = poe->lowerstack[i].dentry;
1157 this = lookup_positive_unlocked(name->name, lowerdir,
1160 switch (PTR_ERR(this)) {
1167 * Assume something is there, we just couldn't
1174 positive = !ovl_is_whiteout(this);
1179 revert_creds(old_cred);