diff options
| author | KONDO KAZUMA(近藤 和真) <kazuma-kondo@nec.com> | 2025-05-15 12:18:30 +0000 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2025-06-07 00:41:02 -0400 |
| commit | 4954346d80fb047cb78776d9f2ebd6a050f80c5f (patch) | |
| tree | bdd2a68ece3b0751e6b9c8a54d0d2ca1102c2768 /fs/namespace.c | |
| parent | d8cc0362f918d020ca1340d7694f07062dc30f36 (diff) | |
fs: allow clone_private_mount() for a path on real rootfs
Mounting overlayfs with a directory on real rootfs (initramfs)
as upperdir has failed with following message since commit
db04662e2f4f ("fs: allow detached mounts in clone_private_mount()").
[ 4.080134] overlayfs: failed to clone upperpath
Overlayfs mount uses clone_private_mount() to create internal mount
for the underlying layers.
The commit 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 modifying the permission check
of clone_private_mount() following [1].
Reviewed-by: Christian Brauner <brauner@kernel.org>
Fixes: db04662e2f4f ("fs: allow detached mounts in clone_private_mount()")
Link: https://lore.kernel.org/all/20250514190252.GQ2023217@ZenIV/ [1]
Link: https://lore.kernel.org/all/20250506194849.GT2023217@ZenIV/
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Kazuma Kondo <kazuma-kondo@nec.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 6c94ecbe2c2c..854099aafed5 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2493,18 +2493,19 @@ 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 (!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)) + /* + * Make sure the source mount is acceptable. + * Anything mounted in our mount namespace is allowed. + * Otherwise, it must be the root of an anonymous mount + * namespace, and we need to make sure no namespace + * loops get created. + */ + if (!check_mnt(old_mnt)) { + if (!is_mounted(&old_mnt->mnt) || + !is_anon_ns(old_mnt->mnt_ns) || + mnt_has_parent(old_mnt)) return ERR_PTR(-EINVAL); - /* Make sure we don't create mount namespace loops. */ if (!check_for_nsfs_mounts(old_mnt)) return ERR_PTR(-EINVAL); } |