3 files changed, 49 insertions, 1 deletions

diff --git a/fs/mount.h b/fs/mount.h
index 8f2a14ae38a2..8c6a2a651254 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -115,3 +115,12 @@ struct proc_mounts {
 #define proc_mounts(p) (container_of((p), struct proc_mounts, m))
 
 extern const struct seq_operations mounts_op;
+
+extern bool __is_local_mountpoint(struct dentry *dentry);
+static inline bool is_local_mountpoint(struct dentry *dentry)
+{
+	if (!d_mountpoint(dentry))
+		return false;
+
+	return __is_local_mountpoint(dentry);
+}
diff --git a/fs/namei.c b/fs/namei.c
index a7b05bf82d31..a3a14b033b0d 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3565,6 +3565,8 @@ int vfs_rmdir(struct inode *dir, struct dentry *dentry)
 	mutex_lock(&dentry->d_inode->i_mutex);
 
 	error = -EBUSY;
+	if (is_local_mountpoint(dentry))
+		goto out;
 	if (d_mountpoint(dentry))
 		goto out;
 
@@ -3681,7 +3683,7 @@ int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegate
 		return -EPERM;
 
 	mutex_lock(&target->i_mutex);
-	if (d_mountpoint(dentry))
+	if (is_local_mountpoint(dentry) || d_mountpoint(dentry))
 		error = -EBUSY;
 	else {
 		error = security_inode_unlink(dir, dentry);
@@ -4126,6 +4128,8 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		mutex_lock(&target->i_mutex);
 
 	error = -EBUSY;
+	if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry))
+		goto out;
 	if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
 		goto out;
 
diff --git a/fs/namespace.c b/fs/namespace.c
index 044134315f93..77ffdb82f63f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -667,6 +667,41 @@ struct vfsmount *lookup_mnt(struct path *path)
 	return m;
 }
 
+/*
+ * __is_local_mountpoint - Test to see if dentry is a mountpoint in the
+ *                         current mount namespace.
+ *
+ * The common case is dentries are not mountpoints at all and that
+ * test is handled inline.  For the slow case when we are actually
+ * dealing with a mountpoint of some kind, walk through all of the
+ * mounts in the current mount namespace and test to see if the dentry
+ * is a mountpoint.
+ *
+ * The mount_hashtable is not usable in the context because we
+ * need to identify all mounts that may be in the current mount
+ * namespace not just a mount that happens to have some specified
+ * parent mount.
+ */
+bool __is_local_mountpoint(struct dentry *dentry)
+{
+	struct mnt_namespace *ns = current->nsproxy->mnt_ns;
+	struct mount *mnt;
+	bool is_covered = false;
+
+	if (!d_mountpoint(dentry))
+		goto out;
+
+	down_read(&namespace_sem);
+	list_for_each_entry(mnt, &ns->list, mnt_list) {
+		is_covered = (mnt->mnt_mountpoint == dentry);
+		if (is_covered)
+			break;
+	}
+	up_read(&namespace_sem);
+out:
+	return is_covered;
+}
+
 static struct mountpoint *new_mountpoint(struct dentry *dentry)
 {
 	struct hlist_head *chain = mp_hash(dentry);