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authorEric W. Biederman <ebiederm@xmission.com>2012-08-02 08:35:35 -0700
committerEric W. Biederman <ebiederm@xmission.com>2012-11-19 05:59:13 -0800
commit225778d68d98e7cfe2579f8d8b2d7b76f8541b8b (patch)
treed4bc4b78c3e19821eaaffacc5341d02328bcd3c9 /kernel/pid_namespace.c
parentaf4b8a83add95ef40716401395b44a1b579965f4 (diff)
downloadvexpress-lsk-225778d68d98e7cfe2579f8d8b2d7b76f8541b8b.tar.gz
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>
Diffstat (limited to 'kernel/pid_namespace.c')
-rw-r--r--kernel/pid_namespace.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 3cc29b830e9..0dbbc66b6ec 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -146,6 +146,8 @@ 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);
}