4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Amir Goldstein <amir73il@xxxxxxxxx>
commit 2ba9d57e65044859f7ff133bcb0a902769bf3bc6 upstream.
There are several write operations on upper fs not covered by
mnt_want_write():
- test set/remove OPAQUE xattr
- test create O_TMPFILE
- set ORIGIN xattr in ovl_verify_origin()
- cleanup of index entries in ovl_indexdir_cleanup()
Some of these go way back, but this patch only applies over the
v4.14 re-factoring of ovl_fill_super().
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/overlayfs/super.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -520,10 +520,6 @@ static struct dentry *ovl_workdir_create
bool retried = false;
bool locked = false;
- err = mnt_want_write(mnt);
- if (err)
- goto out_err;
-
inode_lock_nested(dir, I_MUTEX_PARENT);
locked = true;
@@ -588,7 +584,6 @@ retry:
goto out_err;
}
out_unlock:
- mnt_drop_write(mnt);
if (locked)
inode_unlock(dir);
@@ -930,12 +925,17 @@ out:
static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
{
+ struct vfsmount *mnt = ofs->upper_mnt;
struct dentry *temp;
int err;
+ err = mnt_want_write(mnt);
+ if (err)
+ return err;
+
ofs->workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false);
if (!ofs->workdir)
- return 0;
+ goto out;
/*
* Upper should support d_type, else whiteouts are visible. Given
@@ -945,7 +945,7 @@ static int ovl_make_workdir(struct ovl_f
*/
err = ovl_check_d_type_supported(workpath);
if (err < 0)
- return err;
+ goto out;
/*
* We allowed this configuration and don't want to break users over
@@ -969,6 +969,7 @@ static int ovl_make_workdir(struct ovl_f
if (err) {
ofs->noxattr = true;
pr_warn("overlayfs: upper fs does not support xattr.\n");
+ err = 0;
} else {
vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE);
}
@@ -980,7 +981,9 @@ static int ovl_make_workdir(struct ovl_f
pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
}
- return 0;
+out:
+ mnt_drop_write(mnt);
+ return err;
}
static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath)
@@ -1027,8 +1030,13 @@ out:
static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe,
struct path *upperpath)
{
+ struct vfsmount *mnt = ofs->upper_mnt;
int err;
+ err = mnt_want_write(mnt);
+ if (err)
+ return err;
+
/* Verify lower root is upper root origin */
err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry,
false, true);
@@ -1056,6 +1064,7 @@ static int ovl_get_indexdir(struct ovl_f
pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
out:
+ mnt_drop_write(mnt);
return err;
}