Mounting overlayfs with a directory on real rootfs (initramfs)
as upperdir has failed with following message since commit [1].
[ 4.080134] overlayfs: failed to clone upperpath
Overlayfs mount uses clone_private_mount() to create internal mount
for the underlying layers.
The commit [1] made clone_private_mount() reject real rootfs because
it does not have a parent mount and is in the initial mount namespace,
that is not an anonymous mount namespace.
This issue can be fixed by relaxing the permission check
of clone_private_mount(), similar to [2].
[1] commit db04662e2f4f ("fs: allow detached mounts in clone_private_mount()")
[2] commit 46f5ab762d04 ("fs: relax mount_setattr() permission checks")
Fixes: db04662e2f4f ("fs: allow detached mounts in clone_private_mount()")
Signed-off-by: Kazuma Kondo <kazuma-kondo@xxxxxxx>
---
fs/namespace.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 1b466c54a357..277dbf18e160 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2482,17 +2482,13 @@ struct vfsmount *clone_private_mount(const struct path *path)
if (IS_MNT_UNBINDABLE(old_mnt))
return ERR_PTR(-EINVAL);
- if (mnt_has_parent(old_mnt)) {
+ if (!is_mounted(&old_mnt->mnt))
+ return ERR_PTR(-EINVAL);
+
+ if (mnt_has_parent(old_mnt) || !is_anon_ns(old_mnt->mnt_ns)) {
if (!check_mnt(old_mnt))
return ERR_PTR(-EINVAL);
} else {
- if (!is_mounted(&old_mnt->mnt))
- return ERR_PTR(-EINVAL);
-
- /* Make sure this isn't something purely kernel internal. */
- if (!is_anon_ns(old_mnt->mnt_ns))
- return ERR_PTR(-EINVAL);
-
/* Make sure we don't create mount namespace loops. */
if (!check_for_nsfs_mounts(old_mnt))
return ERR_PTR(-EINVAL);
--
2.49.0
