Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753233Ab3IJR0o (ORCPT ); Tue, 10 Sep 2013 13:26:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:15500 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751872Ab3IJR0n (ORCPT ); Tue, 10 Sep 2013 13:26:43 -0400 Date: Tue, 10 Sep 2013 19:20:33 +0200 From: Oleg Nesterov To: Steve Grubb Cc: linux-audit@redhat.com, Richard Guy Briggs , linux-kernel@vger.kernel.org, Kees Cook , Eric Paris Subject: Re: audit looks unmaintained? [was: Re: [PATCH 11/12] pid: rewrite task helper functions avoiding task->pid and task->tgid] Message-ID: <20130910172033.GA6585@redhat.com> References: <20130827171134.GB29147@redhat.com> <20130830190646.GA30331@madcap2.tricolour.ca> <3996102.evTQ9SbNnV@x2> <20130908155435.GC4663@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130908155435.GC4663@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3177 Lines: 83 On 09/08, Oleg Nesterov wrote: > > First of all, I do not pretend I understand this code. This was mostly > the question, and in fact I mostly asked about audit_bprm() in 0/1. > > However, > > On 08/30, Steve Grubb wrote: > > On Friday, August 30, 2013 03:06:46 PM Richard Guy Briggs wrote: > > > On Tue, Aug 27, 2013 at 07:11:34PM +0200, Oleg Nesterov wrote: > > > > Btw. audit looks unmaintained... if you are going to take care of > > > > this code, perhaps you can look at > > > > > > > > http://marc.info/?l=linux-kernel&m=137589907108485 > > > > http://marc.info/?l=linux-kernel&m=137590271809664 > > > > You don't want to clear the TIF audit flag when context == NULL. What that will > > do is make a bunch of inauditable processes. There are times when audit is > > disabled and then re-enabled later. If the flag gets cleared, then a task's > > syscall will never enter the auditing framework from kernel/entry_64.S. > > > > That flag is 0 when auditing has never ever been enabled. If auditing is > > enabled, it should always be a 1 unless the task filter has determined that > > this process should not be audited ever. In practice, this is almost never > > used. But ensuring the TIF_SYSCALL_AUDIT set to 1 on all processes is why we > > have the boot argument. Not setting audit=1 on the boot arguments means that > > any process running before the audit daemon enables auditing can never ever be > > audited because the only place its set is when processes are cloned. > > Then why audit_alloc() doesn't set TIF_SYSCALL_AUDIT unconditionally? > > And I do not understand "when context == NULL" above. Say, audit_syscall_entry() > does nothing if !audit_context, and nobody except copy_process() does > audit_alloc(). So why do we need to trigger the audit's paths if it is NULL? > > > Hope this clears up the use. NAK to the patch, it'll break auditing. > > Not really, but thanks for your reply anyway. So, Steve, do you still think that patch was wrong? Attached below just in case. Oleg. [PATCH 1/1] audit_alloc: clear TIF_SYSCALL_AUDIT if !audit_context If audit_filter_task() nacks the new thread it makes sense to clear TIF_SYSCALL_AUDIT which can be copied from parent by dup_task_struct(). A wrong TIF_SYSCALL_AUDIT is not really bad, but it triggers the "slow" audit paths in entry.S. Signed-off-by: Oleg Nesterov --- kernel/auditsc.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 9845cb3..95293ab 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -943,8 +943,10 @@ int audit_alloc(struct task_struct *tsk) return 0; /* Return if not auditing. */ state = audit_filter_task(tsk, &key); - if (state == AUDIT_DISABLED) + if (state == AUDIT_DISABLED) { + clear_tsk_thread_flag(tsk, TIF_SYSCALL_AUDIT); return 0; + } if (!(context = audit_alloc_context(state))) { kfree(key); -- 1.5.5.1 -- 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/