Directory index entries should have origin xattr pointing to the
real upper dir. Non-dir index entries are hardlinks to the upper
real inode. For non-dir index, we can read the copy up origin xattr
directly from the index dentry, but for dir index we first need to
decode the upper directory.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/namei.c | 60 +++++++++++++++++++++++++++++++++---------------
fs/overlayfs/overlayfs.h | 4 ++--
fs/overlayfs/readdir.c | 2 +-
3 files changed, 45 insertions(+), 21 deletions(-)
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 1afc6d6e99b9..aba57d31d850 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -391,36 +391,45 @@ int ovl_verify_origin(struct dentry *dentry, struct dentry *origin,
goto out;
}
+/* Get upper dentry from index */
+struct dentry *ovl_index_upper(struct dentry *index, struct vfsmount *mnt)
+{
+ struct path upperpath = { .mnt = mnt };
+ struct path *stack = &upperpath;
+ unsigned int ctr = 0;
+ int err;
+
+ if (!d_is_dir(index))
+ return dget(index);
+
+ err = ovl_check_origin(index, stack, 1, &stack, &ctr);
+ if (!err && !ctr)
+ err = -ENODATA;
+ if (err)
+ return ERR_PTR(err);
+
+ return upperpath.dentry;
+}
+
/*
* Verify that an index entry name matches the origin file handle stored in
* OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path.
* Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error.
*/
-int ovl_verify_index(struct dentry *index, struct path *lowerstack,
- unsigned int numlower)
+int ovl_verify_index(struct dentry *index, struct vfsmount *mnt,
+ struct path *lowerstack, unsigned int numlower)
{
struct ovl_fh *fh = NULL;
size_t len;
struct path origin = { };
struct path *stack = &origin;
unsigned int ctr = 0;
+ struct dentry *upper = NULL;
int err;
if (!d_inode(index))
return 0;
- /*
- * Directory index entries are going to be used for looking up
- * redirected upper dirs by lower dir fh when decoding an overlay
- * file handle of a merge dir. We don't know the verification rules
- * for directory index entries, because they have not been implemented
- * yet, so return EROFS if those entries are found to avoid corrupting
- * an index that was created by a newer kernel.
- */
- err = -EROFS;
- if (d_is_dir(index))
- goto fail;
-
err = -EINVAL;
if (index->d_name.len < sizeof(struct ovl_fh)*2)
goto fail;
@@ -446,23 +455,38 @@ int ovl_verify_index(struct dentry *index, struct path *lowerstack,
if (ovl_is_whiteout(index))
goto out;
- err = ovl_verify_origin_fh(index, fh);
+ /*
+ * Directory index entries should have origin xattr pointing to the
+ * real upper dir. Non-dir index entries are hardlinks to the upper
+ * real inode. For non-dir index, we can read the copy up origin xattr
+ * directly from the index dentry, but for dir index we first need to
+ * decode the upper directory.
+ */
+ upper = ovl_index_upper(index, mnt);
+ if (IS_ERR(upper)) {
+ err = PTR_ERR(upper);
+ if (err)
+ goto fail;
+ }
+
+ err = ovl_verify_origin_fh(upper, fh);
if (err)
goto fail;
- err = ovl_check_origin(index, lowerstack, numlower, &stack, &ctr);
+ err = ovl_check_origin(upper, lowerstack, numlower, &stack, &ctr);
if (!err && !ctr)
err = -ESTALE;
if (err)
goto fail;
/* Check if index is orphan and don't warn before cleaning it */
- if (d_inode(index)->i_nlink == 1 &&
+ if (!d_is_dir(index) && d_inode(index)->i_nlink == 1 &&
ovl_get_nlink(index, origin.dentry, 0) == 0)
err = -ENOENT;
- dput(origin.dentry);
out:
+ dput(origin.dentry);
+ dput(upper);
kfree(fh);
return err;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 35f5452e61e0..e4caad7bae19 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -263,8 +263,8 @@ static inline bool ovl_is_impuredir(struct dentry *dentry)
/* namei.c */
int ovl_verify_origin(struct dentry *dentry, struct dentry *origin,
bool is_upper, bool set);
-int ovl_verify_index(struct dentry *index, struct path *lowerstack,
- unsigned int numlower);
+int ovl_verify_index(struct dentry *index, struct vfsmount *mnt,
+ struct path *lowerstack, unsigned int numlower);
int ovl_get_index_name(struct dentry *origin, struct qstr *name);
int ovl_path_next(int idx, struct dentry *dentry, struct path *path, int *idxp);
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags);
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index ba44546ad1ed..479ce47ba411 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -1055,7 +1055,7 @@ int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt,
index = NULL;
break;
}
- err = ovl_verify_index(index, lowerstack, numlower);
+ err = ovl_verify_index(index, mnt, lowerstack, numlower);
if (err) {
if (err == -EROFS)
break;
--
2.7.4
--
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