Messages in this thread Patch in this message | | | From | "Eric W. Biederman" <> | Date | Fri, 16 Nov 2012 08:35:45 -0800 | Subject | [PATCH 06/11] pidns: Don't allow new processes in a dead pid namespace. |
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From: "Eric W. Biederman" <ebiederm@xmission.com>
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" <serge@hallyn.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> --- kernel/pid.c | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/kernel/pid.c b/kernel/pid.c index e957f8b..9c21911 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); -- 1.7.5.4
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