Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758284AbZD2A3d (ORCPT ); Tue, 28 Apr 2009 20:29:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754148AbZD2A3Y (ORCPT ); Tue, 28 Apr 2009 20:29:24 -0400 Received: from tundra.namei.org ([65.99.196.166]:52199 "EHLO tundra.namei.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754121AbZD2A3X (ORCPT ); Tue, 28 Apr 2009 20:29:23 -0400 Date: Wed, 29 Apr 2009 10:29:06 +1000 (EST) From: James Morris To: Oleg Nesterov cc: David Howells , Eric Paris , Roland McGrath , Stephen Smalley , linux-kernel@vger.kernel.org Subject: Re: Q: selinux_bprm_committed_creds() && signals/do_wait In-Reply-To: <20090428223025.GA11997@redhat.com> Message-ID: References: <20090428223025.GA11997@redhat.com> User-Agent: Alpine 2.00 (LRH 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1701 Lines: 54 On Wed, 29 Apr 2009, Oleg Nesterov wrote: > selinux_bprm_committed_creds: > > rc = avc_has_perm() > if (rc) { > flush_signals(current); > > This doesn't look right. If the task was SIGKILL'ed we must not proceed, > the task should die. The fix is simple, we should check SIGNAL_GROUP_EXIT > and do nothing in this case, the task will exit before return to user > space. If SIGNAL_GROUP_EXIT is set, it is just wrong to drop SIGKILL and > continue. I'm not quite sure what you're asking. This is a permission check to see if the new task can inherit the signal state of the parent, and if not, the new task's signal state is flushed. Where does a consideration of SIGKILL arise? > But, before fixing, I'd like to understand why we are doing > > flush_signal_handlers(current, 1); > sigemptyset(¤t->blocked); > > later. Could someone explain ? This looks unneeded. This is part of clearing all the signal state in the child. > > > Another question, > > wake_up_interruptible(¤t->parent->signal->wait_chldexit); > > Shouldn't we use ->real_parent ? Afaics, we shouldn't worry about the tracer > if current is ptraced, exec must not succeed if the tracer has no rights to > trace this task after cred changing. But we should notify ->real_parent which > is, well, real parent. > > Also, we don't need _irq to take tasklist_lock, and we don't actually need > ->siglock. > > Oleg. > -- James Morris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/