+
+static void *mntns_get(struct task_struct *task)
+{
+ struct mnt_namespace *ns = NULL;
+ struct nsproxy *nsproxy;
+
+ rcu_read_lock();
+ nsproxy = task_nsproxy(task);
+ if (nsproxy) {
+ ns = nsproxy->mnt_ns;
+ get_mnt_ns(ns);
+ }
+ rcu_read_unlock();
+
+ return ns;
+}
+
+static void mntns_put(void *ns)
+{
+ put_mnt_ns(ns);
+}
+
+static int mntns_install(struct nsproxy *nsproxy, void *ns)
+{
+ struct fs_struct *fs = current->fs;
+ struct mnt_namespace *mnt_ns = ns;
+ struct path root;
+
+ if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
+ !nsown_capable(CAP_SYS_CHROOT) ||
+ !nsown_capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (fs->users != 1)
+ return -EINVAL;
+
+ get_mnt_ns(mnt_ns);
+ put_mnt_ns(nsproxy->mnt_ns);
+ nsproxy->mnt_ns = mnt_ns;
+
+ /* Find the root */
+ root.mnt = &mnt_ns->root->mnt;
+ root.dentry = mnt_ns->root->mnt.mnt_root;
+ path_get(&root);
+ while(d_mountpoint(root.dentry) && follow_down_one(&root))
+ ;
+
+ /* Update the pwd and root */
+ set_fs_pwd(fs, &root);
+ set_fs_root(fs, &root);
+
+ path_put(&root);
+ return 0;
+}
+
+static unsigned int mntns_inum(void *ns)
+{
+ struct mnt_namespace *mnt_ns = ns;
+ return mnt_ns->proc_inum;
+}
+
+const struct proc_ns_operations mntns_operations = {
+ .name = "mnt",
+ .type = CLONE_NEWNS,
+ .get = mntns_get,
+ .put = mntns_put,
+ .install = mntns_install,
+ .inum = mntns_inum,
+};