From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933688AbbIDU6c (ORCPT ); Fri, 4 Sep 2015 16:58:32 -0400 Received: from mail-yk0-f176.google.com ([209.85.160.176]:36255 "EHLO mail-yk0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932856AbbIDU6b (ORCPT ); Fri, 4 Sep 2015 16:58:31 -0400 Date: Fri, 4 Sep 2015 13:58:25 -0700 From: Alexei Starovoitov To: Kees Cook Cc: Tycho Andersen , Alexei Starovoitov , Will Drewry , Oleg Nesterov , Andy Lutomirski , Pavel Emelyanov , "Serge E. Hallyn" , Daniel Borkmann , LKML , Network Development Subject: Re: [PATCH 3/6] ebpf: add a way to dump an eBPF program Message-ID: <20150904205821.GE1842@Alexeis-MacBook-Pro-2.local> References: <1441382664-17437-1-git-send-email-tycho.andersen@canonical.com> <1441382664-17437-4-git-send-email-tycho.andersen@canonical.com> <20150904204554.GO26679@smitten> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 04, 2015 at 01:50:55PM -0700, Kees Cook wrote: > On Fri, Sep 4, 2015 at 1:45 PM, Tycho Andersen > wrote: > > On Fri, Sep 04, 2015 at 01:17:30PM -0700, Kees Cook wrote: > >> On Fri, Sep 4, 2015 at 9:04 AM, Tycho Andersen > >> wrote: > >> > This commit adds a way to dump eBPF programs. The initial implementation > >> > doesn't support maps, and therefore only allows dumping seccomp ebpf > >> > programs which themselves don't currently support maps. > >> > > >> > We export the GPL bit as well as a unique ID for the program so that > >> > >> This unique ID appears to be the heap address for the prog. That's a > >> huge leak, and should not be done. We don't want to introduce new > >> kernel address leaks while we're trying to fix the remaining ones. > >> Shouldn't the "unique ID" be the fd itself? I imagine KCMP_FILE > >> could be used, for example. > > > > No; we acquire the fd per process, so if a task installs a filter and > > then forks N times, we'll grab N (+1) copies of the filter from N (+1) > > different file descriptors. Ideally, we'd have some way to figure out > > that these were all the same. Some sort of prog_id is one way, > > although there may be others. > > If KCMP_FILE or a new KCMP_BPF isn't possible, then we'll probably > have to add a unique id (counter) to all bpf programs as they're > created. I think tweaking KCMP_FILE for anon_inodes should do the trick and should work at the end (if it's not working already).