Eric Lee / smarc-ti-linux-kernel | Embedian Git Server

Commit 225778d68d98e7cfe2579f8d8b2d7b76f8541b8b

Authored by Eric W. Biederman 2012-08-02 23:35:35 +0800

pidns: Deny strange cases when creating pid namespaces.

task_active_pid_ns(current) != current->ns_proxy->pid_ns will
soon be allowed to support unshare and setns.

The definition of creating a child pid namespace when
task_active_pid_ns(current) != current->ns_proxy->pid_ns could be that
we create a child pid namespace of current->ns_proxy->pid_ns.  However
that leads to strange cases like trying to have a single process be
init in multiple pid namespaces, which is racy and hard to think
about.

The definition of creating a child pid namespace when
task_active_pid_ns(current) != current->ns_proxy->pid_ns could be that
we create a child pid namespace of task_active_pid_ns(current).  While
that seems less racy it does not provide any utility.

Therefore define the semantics of creating a child pid namespace when
task_active_pid_ns(current) != current->ns_proxy->pid_ns to be that the
pid namespace creation fails.  That is easy to implement and easy
to think about.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Showing 1 changed file with 2 additions and 0 deletions Side-by-side Diff

kernel/pid_namespace.c

kernel/pid_namespace.c

Diff comments View file @ 225778d

...	...	@@ -146,6 +146,8 @@
146	146	return get_pid_ns(old_ns);
147	147	if (flags & (CLONE_THREAD\|CLONE_PARENT))
148	148	return ERR_PTR(-EINVAL);
	149	+ if (task_active_pid_ns(current) != old_ns)
	150	+ return ERR_PTR(-EINVAL);
149	151	return create_pid_namespace(user_ns, old_ns);
150	152	}
151	153