From 5e1182deb81ae8c68494017c4a8a71811659c870 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 12 Jul 2010 18:50:25 -0700 Subject: pidns: Don't allow new processes in a dead pid namespace. Set nr_hashed to -1 just before we schedule the work to cleanup proc. Test nr_hashed just before we hash a new pid and if nr_hashed is < 0 fail. This guaranteees that processes never enter a pid namespaces after we have cleaned up the state to support processes in a pid namespace. Currently sending SIGKILL to all of the process in a pid namespace as init exists gives us this guarantee but we need something a little stronger to support unsharing and joining a pid namespace. Acked-by: "Serge E. Hallyn" Signed-off-by: Eric W. Biederman --- kernel/pid.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/pid.c b/kernel/pid.c index e957f8b09136..9c219117af36 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -274,8 +274,10 @@ void free_pid(struct pid *pid) for (i = 0; i <= pid->level; i++) { struct upid *upid = pid->numbers + i; hlist_del_rcu(&upid->pid_chain); - if (--upid->ns->nr_hashed == 0) + if (--upid->ns->nr_hashed == 0) { + upid->ns->nr_hashed = -1; schedule_work(&upid->ns->proc_work); + } } spin_unlock_irqrestore(&pidmap_lock, flags); @@ -321,6 +323,8 @@ struct pid *alloc_pid(struct pid_namespace *ns) upid = pid->numbers + ns->level; spin_lock_irq(&pidmap_lock); + if (ns->nr_hashed < 0) + goto out_unlock; for ( ; upid >= pid->numbers; --upid) { hlist_add_head_rcu(&upid->pid_chain, &pid_hash[pid_hashfn(upid->nr, upid->ns)]); @@ -331,6 +335,8 @@ struct pid *alloc_pid(struct pid_namespace *ns) out: return pid; +out_unlock: + spin_unlock(&pidmap_lock); out_free: while (++i <= ns->level) free_pidmap(pid->numbers + i); -- cgit v1.2.2