Quoting sukadev@xxxxxxxxxx (sukadev@xxxxxxxxxx): > > Subject: Enable signaling child reaper from parent ns. > > From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx> > > The reaper of a child namespace must receive signals from its parent pid > namespace but not receive any signals from its own namespace. > > This is a very early draft :-) and following tests seem to pass > > - Successfully kill child reaper from parent namespace (init_pid_ns) > > - Fail to kill child reaper from within its namespace (non init_pid_ns) > > - kill -1 1 from init_pid_ns seemed to work (rescanned inittab) > > TODO: > - Test async io and SIGIO delivery. > > - Allow any legitimate signals that the child reaper can receive > from within its namespace? (we block all signals now) > > - Sending SIGKILL to the child reaper of a namespace terminates the > namespace But if the namespace remounted /proc from user space, > /proc would remain mounted even after reaper and other process in > the namespace go away. > > Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx> > --- > kernel/signal.c | 22 +++++++++++++++++++++- > 1 file changed, 21 insertions(+), 1 deletion(-) > > Index: lx26-21-mm2/kernel/signal.c > =================================================================== > --- lx26-21-mm2.orig/kernel/signal.c 2007-05-22 16:59:42.000000000 -0700 > +++ lx26-21-mm2/kernel/signal.c 2007-05-22 16:59:57.000000000 -0700 > @@ -507,6 +507,20 @@ static int check_kill_permission(int sig > && !capable(CAP_KILL)) > return error; > > + /* > + * If t is the reaper of its namespace and someone from that > + * namespace is trying to send a signal. > + * > + * Note: If some one from parent namespace is sending a signal, > + * task_child_reaper() != t and we allow the signal. > + * > + * In the child namespace, does this block even legitimate signals > + * like the ones telinit sends to /sbin/init ? > + * > + */ > + if ((!is_global_init(t)) && (t == task_child_reaper(t))) Couldn't you more clearly achieve what you want by doing: if ((!is_global_init(t)) && (t == task_child_reaper(current))) Still like you say I think you need to study more how current code does the right thing for the global init. Reproduce exactly that if t == task_child_reaper(current), else treat like any other task. And though I said "reproduce", I should think you could do it without separate checks as you have here. -serge > + return -EPERM; > + > error = security_task_kill(t, info, sig, 0); > if (!error) > audit_signal_info(sig, t); /* Let audit system see the signal */ > @@ -1910,7 +1924,13 @@ relock: > /* > * Init of a pid space gets no signals it doesn't want from > * within that pid space. It can of course get signals from > - * its parent pid space. > + * its parent pid space. But we have no way of knowing the > + * namespace from which the signal was sent. For now check > + * if we are global init here and add additional checks in > + * sys_kill() and friends. > + * > + * Note that t == task_child_reaper(t) implies t is the global > + * init (and we are in init_pid_ns). > */ > if (current == task_child_reaper(current)) > continue; _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers