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=-2.5 required=3.0 tests=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 42DC1C3A5A2 for ; Tue, 10 Sep 2019 05:35:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 197DF21928 for ; Tue, 10 Sep 2019 05:35:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393168AbfIJFfN (ORCPT ); Tue, 10 Sep 2019 01:35:13 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:2259 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2390795AbfIJFfM (ORCPT ); Tue, 10 Sep 2019 01:35:12 -0400 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id D4E906A0A81874DC646C; Tue, 10 Sep 2019 13:35:09 +0800 (CST) Received: from [127.0.0.1] (10.177.96.203) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.439.0; Tue, 10 Sep 2019 13:35:01 +0800 Subject: Re: [PATCH v6 00/12] implement KASLR for powerpc/fsl_booke/32 To: Scott Wood , , , , , , , , , CC: , , , , , , References: <20190809100800.5426-1-yanaijie@huawei.com> From: Jason Yan Message-ID: Date: Tue, 10 Sep 2019 13:34:59 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.96.203] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Scott, On 2019/8/28 12:05, Scott Wood wrote: > 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. > How did you change the load address of the uImage, by changing the kernel config CONFIG_PHYSICAL_START or the "-a/-e" parameter of mkimage? I tried both, but it did not work with or without CONFIG_RANDOMIZE. Thanks, Jason >> 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 > > > > . >