From: Miklos Szeredi mszeredi@redhat.com
stable inclusion from linux-4.19.204 commit 963d85d630dabe75a3cfde44a006fec3304d07b8
--------------------------------
commit 427215d85e8d1476da1a86b8d67aceb485eb3631 upstream.
Add the following checks from __do_loopback() to clone_private_mount() as well:
- verify that the mount is in the current namespace
- verify that there are no locked children
Reported-by: Alois Wohlschlager alois1@gmx-topmail.de Fixes: c771d683a62e ("vfs: introduce clone_private_mount()") Cc: stable@vger.kernel.org # v3.18 Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- fs/namespace.c | 42 ++++++++++++++++++++++++++++-------------- 1 file changed, 28 insertions(+), 14 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c index c582abcdab598..bc774f3be8b86 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1852,6 +1852,20 @@ void drop_collected_mounts(struct vfsmount *mnt) namespace_unlock(); }
+static bool has_locked_children(struct mount *mnt, struct dentry *dentry) +{ + struct mount *child; + + list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { + if (!is_subdir(child->mnt_mountpoint, dentry)) + continue; + + if (child->mnt.mnt_flags & MNT_LOCKED) + return true; + } + return false; +} + /** * clone_private_mount - create a private clone of a path * @@ -1866,14 +1880,27 @@ struct vfsmount *clone_private_mount(const struct path *path) struct mount *old_mnt = real_mount(path->mnt); struct mount *new_mnt;
+ down_read(&namespace_sem); if (IS_MNT_UNBINDABLE(old_mnt)) - return ERR_PTR(-EINVAL); + goto invalid; + + if (!check_mnt(old_mnt)) + goto invalid; + + if (has_locked_children(old_mnt, path->dentry)) + goto invalid;
new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); + up_read(&namespace_sem); + if (IS_ERR(new_mnt)) return ERR_CAST(new_mnt);
return &new_mnt->mnt; + +invalid: + up_read(&namespace_sem); + return ERR_PTR(-EINVAL); } EXPORT_SYMBOL_GPL(clone_private_mount);
@@ -2189,19 +2216,6 @@ static int do_change_type(struct path *path, int ms_flags) return err; }
-static bool has_locked_children(struct mount *mnt, struct dentry *dentry) -{ - struct mount *child; - list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { - if (!is_subdir(child->mnt_mountpoint, dentry)) - continue; - - if (child->mnt.mnt_flags & MNT_LOCKED) - return true; - } - return false; -} - /* * do loopback mount. */