Messages in this thread Patch in this message | | | From | "Eric W. Biederman" <> | Date | Fri, 16 Nov 2012 08:35:47 -0800 | Subject | [PATCH 08/11] pidns: Deny strange cases when creating pid namespaces. |
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From: "Eric W. Biederman" <ebiederm@xmission.com>
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> --- kernel/pid_namespace.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index e106b18..066c058 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -145,6 +145,8 @@ struct pid_namespace *copy_pid_ns(unsigned long flags, return get_pid_ns(old_ns); if (flags & (CLONE_THREAD|CLONE_PARENT)) return ERR_PTR(-EINVAL); + if (task_active_pid_ns(current) != old_ns) + return ERR_PTR(-EINVAL); return create_pid_namespace(user_ns, old_ns); } -- 1.7.5.4
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