From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC7F9C48BE5 for ; Tue, 15 Jun 2021 12:53:29 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0882861466 for ; Tue, 15 Jun 2021 12:53:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0882861466 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4G47Xm1pBrz3bvH for ; Tue, 15 Jun 2021 22:53:28 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=permerror (SPF Permanent Error: Unknown mechanism found: ip:192.40.192.88/32) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lists.ozlabs.org (Postfix) with ESMTP id 4G47XM3Bjgz302y for ; Tue, 15 Jun 2021 22:53:05 +1000 (AEST) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 15FCowXA024371; Tue, 15 Jun 2021 07:50:58 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 15FCov2C024367; Tue, 15 Jun 2021 07:50:57 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Tue, 15 Jun 2021 07:50:57 -0500 From: Segher Boessenkool To: Jessica Yu Subject: Re: [PATCH v4 1/2] module: add elf_check_module_arch for module specific elf arch checks Message-ID: <20210615125057.GF5077@gate.crashing.org> References: <20210611093959.821525-1-npiggin@gmail.com> <20210611093959.821525-2-npiggin@gmail.com> <1623722110.amu32mwaqs.astroid@bobo.none> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michal =?iso-8859-1?Q?Such=E1nek?= , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Nicholas Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Jun 15, 2021 at 02:17:40PM +0200, Jessica Yu wrote: > +int __weak elf_check_module_arch(Elf_Ehdr *hdr) > +{ > + return 1; > +} But is this a good idea? It isn't useful to be able to attempt to load a module not compiled for your architecture, and it increases the attack surface tremendously. These checks are one of the few things that can *not* be weak symbols, imo. Segher