From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754708Ab2B0Uf3 (ORCPT ); Mon, 27 Feb 2012 15:35:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:3974 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754390Ab2B0Uf0 (ORCPT ); Mon, 27 Feb 2012 15:35:26 -0500 Message-ID: <1330374879.2542.24.camel@localhost> Subject: Re: [PATCH v11 06/12] seccomp: add system call filtering using BPF From: Eric Paris To: Kees Cook Cc: Will Drewry , Kees Cook , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, kernel-hardening@lists.openwall.com, netdev@vger.kernel.org, x86@kernel.org, arnd@arndb.de, davem@davemloft.net, hpa@zytor.com, mingo@redhat.com, oleg@redhat.com, peterz@infradead.org, rdunlap@xenotime.net, mcgrathr@chromium.org, tglx@linutronix.de, luto@mit.edu, serge.hallyn@canonical.com, djm@mindrot.org, scarybeasts@gmail.com, indan@nul.nu, pmoore@redhat.com, akpm@linux-foundation.org, corbet@lwn.net, eric.dumazet@gmail.com, markus@chromium.org, coreyb@linux.vnet.ibm.com Date: Mon, 27 Feb 2012 15:34:39 -0500 In-Reply-To: References: <1330140111-17201-1-git-send-email-wad@chromium.org> <1330140111-17201-6-git-send-email-wad@chromium.org> <20120226202828.GE3990@outflux.net> <1330361396.2542.11.camel@localhost> <1330370733.2542.18.camel@localhost> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-02-27 at 12:00 -0800, Kees Cook wrote: > On Mon, Feb 27, 2012 at 11:25 AM, Eric Paris wrote: > > On Mon, 2012-02-27 at 10:55 -0800, Kees Cook wrote: > >> On Mon, Feb 27, 2012 at 8:49 AM, Eric Paris wrote: > > > >> You mean as used in audit_log_exit() ? It looks like that depends on a > >> lot of state cached in __audit_syscall_entry() and finally triggered > >> in __audit_syscall_exit() (and ..._free()). I don't think this is > >> really want seccomp wants to be involved in. > >> > >> By CONFIG_AUDITSC, you mean CONFIG_AUDITSYSCALL? Without that set, > >> audit_seccomp is a no-op. > >> > >> The reason compat needs to be reported (or rather, arch) is because > >> just reporting syscall is ambiguous. It either needs arch or compat to > >> distinguish it. > > > > Yes, that is what I mean and you are right. You shouldn't push the > > syscall in this record either. If !audit_dummy_context() you are > > already going to get arch, syscall, and a0-a4 in the associated audit > > record. Please do not duplicate that info. > > Ah, in that case, please ignore the patch I just sent. Heh. > > > It might make sense to have a separate audit_seccomp() path when > > audit_dummy_context() which includes arch, syscall, and a0-a4. > > Ah! I think I understand what you mean now. If audit_dummy_context(), > then the syscall, arch, and a0-a4 were not already collected. Gotcha. > > How do you envision it looking? I still see it as two distinct events > (the syscall itself, and the rejection). Would you want those details > added to the context structure to be reported at ..._exit() time? It > seems like context->type couldn't be used to see if those fields were > valid. > > Something like: > > void __audit_seccomp(unsigned long syscall, long signr) > { > struct audit_buffer *ab; > > if (!audit_dummy_context()) { > struct audit_context *context = current->audit_context; > context->syscall_signr = signr; > context->syscall_ip = KSTK_EIP(current); > return; > } > > ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_ANOM_ABEND); > audit_log_abend(ab, "seccomp", signr); > audit_log_format(ab, " syscall=%ld", syscall); > audit_log_format(ab, " ip=0x%lx", KSTK_EIP(current)); > audit_log_end(ab); > } > > And then report syscall_ip and syscall_signr if syscall_signr != 0 in > the _exit()? I think everything else from audit_log_abend() will end > up in the _exit() report. > > > It is my fault (85e7bac3) that we have syscall at all, but I'm on a new > > crusade to remove audit record duplication. So I'd happily see a patch > > in this series that removes that instead of adds to it. > > Well, I think the abend reporting is nice; I'd hate to see that > totally removed. The seccomp case is a bit different, I agree. I could > see it either way. Once again I send you down a bad path. Your original patch was the best. We should consider including a0-aX in a future version. I was mistaken in foolishly believing that audit_syscall_entry() was done before secure_computing(). But if you look, that isn't the case. Please pretend I never said anything as you had it right the first time. -Eric