From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tycho Andersen Subject: Re: [PATCH 3/6] ebpf: add a way to dump an eBPF program Date: Fri, 4 Sep 2015 14:45:54 -0600 Message-ID: <20150904204554.GO26679@smitten> References: <1441382664-17437-1-git-send-email-tycho.andersen@canonical.com> <1441382664-17437-4-git-send-email-tycho.andersen@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Alexei Starovoitov , Will Drewry , Oleg Nesterov , Andy Lutomirski , Pavel Emelyanov , "Serge E. Hallyn" , Daniel Borkmann , LKML , Network Development To: Kees Cook Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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. Tycho