Commit e4da026f authored Apr 02, 2009 by Sukadev Bhattiprolu Committed by Linus Torvalds Apr 02, 2009

signals: zap_pid_ns_process() should use force_sig()



send_signal() assumes that signals with SEND_SIG_PRIV are generated from
within the same namespace.  So any nested container-init processes become
immune to the SIGKILL generated by kill_proc_info() in
zap_pid_ns_processes().

Use force_sig() in zap_pid_ns_processes() instead - force_sig() clears the
SIGNAL_UNKILLABLE flag ensuring the signal is processed by
container-inits.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 921cf9f6

kernel/pid_namespace.c

+14 −1

Original line number	Diff line number	Diff line
		@@ -152,6 +152,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
		{
		int nr;
		int rc;
		struct task_struct *task;

		/*
		* The last thread in the cgroup-init thread group is terminating.
		@@ -169,7 +170,19 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
		read_lock(&tasklist_lock);
		nr = next_pidmap(pid_ns, 1);
		while (nr > 0) {
		kill_proc_info(SIGKILL, SEND_SIG_PRIV, nr);
		rcu_read_lock();

		/*
		* Use force_sig() since it clears SIGNAL_UNKILLABLE ensuring
		* any nested-container's init processes don't ignore the
		* signal
		*/
		task = pid_task(find_vpid(nr), PIDTYPE_PID);
		if (task)
		force_sig(SIGKILL, task);

		rcu_read_unlock();

		nr = next_pidmap(pid_ns, nr);
		}
		read_unlock(&tasklist_lock);

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