Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754469Ab2B0SJn (ORCPT ); Mon, 27 Feb 2012 13:09:43 -0500 Received: from mail-tul01m020-f174.google.com ([209.85.214.174]:50033 "EHLO mail-tul01m020-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754280Ab2B0SJl convert rfc822-to-8bit (ORCPT ); Mon, 27 Feb 2012 13:09:41 -0500 Authentication-Results: mr.google.com; spf=pass (google.com: domain of keescook@google.com designates 10.60.13.1 as permitted sender) smtp.mail=keescook@google.com; dkim=pass header.i=keescook@google.com MIME-Version: 1.0 In-Reply-To: <20120227171132.GB10608@redhat.com> References: <1330140111-17201-1-git-send-email-wad@chromium.org> <1330140111-17201-7-git-send-email-wad@chromium.org> <20120227171132.GB10608@redhat.com> Date: Mon, 27 Feb 2012 10:09:38 -0800 X-Google-Sender-Auth: cywTo51hOQZTGzQtK_sY-lGRZGM Message-ID: Subject: Re: [PATCH v11 07/12] seccomp: add SECCOMP_RET_ERRNO From: Kees Cook To: Oleg Nesterov Cc: Will Drewry , 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, peterz@infradead.org, rdunlap@xenotime.net, mcgrathr@chromium.org, tglx@linutronix.de, luto@mit.edu, eparis@redhat.com, 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 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1144 Lines: 34 On Mon, Feb 27, 2012 at 9:11 AM, Oleg Nesterov wrote: > On 02/24, Will Drewry wrote: >> >> ?static u32 seccomp_run_filters(int syscall) >> ?{ >> ? ? ? struct seccomp_filter *f; >> - ? ? u32 ret = SECCOMP_RET_KILL; >> ? ? ? static const struct bpf_load_fn fns = { >> ? ? ? ? ? ? ? bpf_load, >> ? ? ? ? ? ? ? sizeof(struct seccomp_data), >> ? ? ? }; >> + ? ? u32 ret = SECCOMP_RET_ALLOW; >> ? ? ? const void *sc_ptr = (const void *)(uintptr_t)syscall; >> >> + ? ? /* Ensure unexpected behavior doesn't result in failing open. */ >> + ? ? if (unlikely(current->seccomp.filter == NULL)) >> + ? ? ? ? ? ? ret = SECCOMP_RET_KILL; > > Is "seccomp.filter == NULL" really possible? It should not be, but I'm much more comfortable with this failing closed. I think it's important to be as defensive as possible with this code given its intended use. -Kees -- Kees Cook ChromeOS Security -- 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/