From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754115Ab1HKVKh (ORCPT ); Thu, 11 Aug 2011 17:10:37 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:52839 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754017Ab1HKVKg (ORCPT ); Thu, 11 Aug 2011 17:10:36 -0400 Date: Thu, 11 Aug 2011 16:09:52 -0500 From: Serge Hallyn To: Daniel Lezcano Cc: akpm@linux-foundation.org, containers@lists.linux-foundation.org, bonbons@linux-vserver.org, oleg@tv-sign.ru, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] Notify container-init parent a 'reboot' occured Message-ID: <20110811210951.GA17349@peqn> References: <1313094241-3674-1-git-send-email-daniel.lezcano@free.fr> <1313094241-3674-3-git-send-email-daniel.lezcano@free.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1313094241-3674-3-git-send-email-daniel.lezcano@free.fr> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting Daniel Lezcano (daniel.lezcano@free.fr): > When the reboot syscall is called and the pid namespace where the calling > process belongs to is not from the init pidns, we send a SIGCHLD with CLD_REBOOTED > to the parent of this pid namespace. > > Signed-off-by: Daniel Lezcano ... > +void do_notify_parent_cldreboot(struct task_struct *tsk, int why, char *buffer) > +{ > + struct siginfo info = { }; > + struct task_struct *parent; > + struct sighand_struct *sighand; > + unsigned long flags; > + > + if (tsk->ptrace) > + parent = tsk->parent; > + else { > + tsk = tsk->group_leader; > + parent = tsk->real_parent; > + } > + > + info.si_signo = SIGCHLD; > + info.si_errno = 0; > + info.si_status = why; > + > + rcu_read_lock(); > + info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns); > + info.si_uid = __task_cred(tsk)->uid; This eventually should become: info.si_uid = user_ns_map_uid(task_cred_xxx(t, user_ns), current_cred(), current_uid()); I've got a first-stab patch at converting the rest of kernel/signal.c in http://kernel.ubuntu.com/git?p=serge/userns-2.6.git > + rcu_read_unlock(); > + > + info.si_utime = cputime_to_clock_t(tsk->utime); > + info.si_stime = cputime_to_clock_t(tsk->stime); > + > + info.si_code = CLD_REBOOTED; > + > + sighand = parent->sighand; > + spin_lock_irqsave(&sighand->siglock, flags); > + if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN && > + sighand->action[SIGCHLD-1].sa.sa_flags & SA_CLDREBOOT) > + __group_send_sig_info(SIGCHLD, &info, parent); > + /* > + * Even if SIGCHLD is not generated, we must wake up wait4 calls. > + */ > + __wake_up_parent(tsk, parent); > + spin_unlock_irqrestore(&sighand->siglock, flags); > +} ... > @@ -426,10 +434,18 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, > { > char buffer[256]; > int ret = 0; > + struct pid_namespace *pid_ns = current->nsproxy->pid_ns; > + > + /* We only trust the superuser with rebooting the system. */ > + if (!capable(CAP_SYS_BOOT)) { Doesn't this mean that an unprivileged task in a container can shut down the container? The pidns->user_ns patch I sent earlier today gives you what you need so that you can add if (!ns_capable(current_pid_ns()->user_ns, CAP_SYS_BOOT) return -EPERM; right here to prevent that. > + /* If we are not in the initial pid namespace, we send a signal > + * to the parent of this init pid namespace, notifying a shutdown > + * occured */ > + if (pid_ns != &init_pid_ns) > + pid_namespace_reboot(pid_ns, cmd, buffer); > > - /* We only trust the superuser with rebooting the system. */ > - if (!capable(CAP_SYS_BOOT)) > return -EPERM; > + } > > /* For safety, we require "magic" arguments. */ > if (magic1 != LINUX_REBOOT_MAGIC1 || > -- > 1.7.4.1 > > _______________________________________________ > Containers mailing list > Containers@lists.linux-foundation.org > https://lists.linux-foundation.org/mailman/listinfo/containers