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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 B9AFBC3A5A1 for ; Wed, 28 Aug 2019 04:12:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B5CB20830 for ; Wed, 28 Aug 2019 04:12:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726146AbfH1EMX (ORCPT ); Wed, 28 Aug 2019 00:12:23 -0400 Received: from baldur.buserror.net ([165.227.176.147]:49074 "EHLO baldur.buserror.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725862AbfH1EMX (ORCPT ); Wed, 28 Aug 2019 00:12:23 -0400 Received: from [2601:449:8400:7293:12bf:48ff:fe84:c9a0] by baldur.buserror.net with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1i2pDA-0007By-1u; Tue, 27 Aug 2019 23:05:32 -0500 Message-ID: From: Scott Wood To: Jason Yan , mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com, christophe.leroy@c-s.fr, benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com, keescook@chromium.org, kernel-hardening@lists.openwall.com Cc: wangkefeng.wang@huawei.com, linux-kernel@vger.kernel.org, jingxiangfeng@huawei.com, zhaohongjiang@huawei.com, thunder.leizhen@huawei.com, fanchengyang@huawei.com, yebin10@huawei.com Date: Tue, 27 Aug 2019 23:05:30 -0500 In-Reply-To: <20190809100800.5426-1-yanaijie@huawei.com> References: <20190809100800.5426-1-yanaijie@huawei.com> Organization: Red Hat Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2601:449:8400:7293:12bf:48ff:fe84:c9a0 X-SA-Exim-Rcpt-To: yanaijie@huawei.com, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com, christophe.leroy@c-s.fr, benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com, keescook@chromium.org, kernel-hardening@lists.openwall.com, wangkefeng.wang@huawei.com, linux-kernel@vger.kernel.org, jingxiangfeng@huawei.com, zhaohongjiang@huawei.com, thunder.leizhen@huawei.com, fanchengyang@huawei.com, yebin10@huawei.com X-SA-Exim-Mail-From: oss@buserror.net Subject: Re: [PATCH v6 00/12] implement KASLR for powerpc/fsl_booke/32 X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on baldur.buserror.net) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2019-08-09 at 18:07 +0800, Jason Yan wrote: > This series implements KASLR for powerpc/fsl_booke/32, as a security > feature that deters exploit attempts relying on knowledge of the location > of kernel internals. > > Since CONFIG_RELOCATABLE has already supported, what we need to do is > map or copy kernel to a proper place and relocate. Have you tested this with a kernel that was loaded at a non-zero address? I tried loading a kernel at 0x04000000 (by changing the address in the uImage, and setting bootm_low to 04000000 in U-Boot), and it works without CONFIG_RANDOMIZE and fails with. > Freescale Book-E > parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1 > entries are not suitable to map the kernel directly in a randomized > region, so we chose to copy the kernel to a proper place and restart to > relocate. > > Entropy is derived from the banner and timer base, which will change every > build and boot. This not so much safe so additionally the bootloader may > pass entropy via the /chosen/kaslr-seed node in device tree. How complicated would it be to directly access the HW RNG (if present) that early in the boot? It'd be nice if a U-Boot update weren't required (and particularly concerning that KASLR would appear to work without a U-Boot update, but without decent entropy). -Scott