[PATCH 1/3] ovl: force read-only sb on failure to create index dir

Amir Goldstein
2020-07-13T14:19:57Z

With index feature enabled, on failure to create index dir, overlay
is being mounted read-only. However, we do not forbid user to remount
overlay read-write. Fix that by setting ofs->workdir to NULL, which
prevents remount read-write.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/overlayfs/super.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 4b7cb2d98203..41d7fe2b8129 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1374,12 +1374,13 @@ static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs,
goto out;
}

+ /* index dir will act also as workdir */
+ iput(ofs->workdir_trap);
+ ofs->workdir_trap = NULL;
+ dput(ofs->workdir);
+ ofs->workdir = NULL;
ofs->indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true);
if (ofs->indexdir) {
- /* index dir will act also as workdir */
- iput(ofs->workdir_trap);
- ofs->workdir_trap = NULL;
- dput(ofs->workdir);
ofs->workdir = dget(ofs->indexdir);

err = ovl_setup_trap(sb, ofs->indexdir, &ofs->indexdir_trap,
@@ -1884,7 +1885,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
if (!ovl_upper_mnt(ofs))
sb->s_flags |= SB_RDONLY;

- if (!(ovl_force_readonly(ofs)) && ofs->config.index) {
+ if (!ovl_force_readonly(ofs) && ofs->config.index) {
err = ovl_get_indexdir(sb, ofs, oe, &upperpath);
if (err)
goto out_free_oe;
--
2.17.1