[PATCH 5/7][v8] zap_pid_ns_process() should use force_sig()

Sukadev Bhattiprolu
2009-02-19T03:07:39Z

From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Date: Wed, 18 Feb 2009 15:12:30 -0800
Subject: [PATCH 5/7][v8] 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>
---
kernel/pid_namespace.c | 14 +++++++++++++-
1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index fab8ea8..33815ae 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -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 +170,18 @@ 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);
+ force_sig(SIGKILL, task);
+
+ rcu_read_unlock();
+
nr = next_pidmap(pid_ns, nr);
}
read_unlock(&tasklist_lock);
--
1.5.2.5