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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 C1EBDC433FF for ; Mon, 29 Jul 2019 11:19:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96C382070D for ; Mon, 29 Jul 2019 11:19:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="TuKAFDEk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387663AbfG2LTo (ORCPT ); Mon, 29 Jul 2019 07:19:44 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:45517 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387554AbfG2LTo (ORCPT ); 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Mon, 29 Jul 2019 13:19:42 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id oGhuO4e1JRma; Mon, 29 Jul 2019 13:19:42 +0200 (CEST) Received: from [172.25.230.101] (po15451.idsi0.si.c-s.fr [172.25.230.101]) by messagerie.si.c-s.fr (Postfix) with ESMTP id D966D8B7B3; Mon, 29 Jul 2019 13:19:41 +0200 (CEST) Subject: Re: [RFC PATCH 08/10] powerpc/fsl_booke/kaslr: clear the original kernel if randomized To: Jason Yan , mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com, benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com, keescook@chromium.org, kernel-hardening@lists.openwall.com Cc: linux-kernel@vger.kernel.org, wangkefeng.wang@huawei.com, yebin10@huawei.com, thunder.leizhen@huawei.com, jingxiangfeng@huawei.com, fanchengyang@huawei.com References: <20190717080621.40424-1-yanaijie@huawei.com> <20190717080621.40424-9-yanaijie@huawei.com> From: Christophe Leroy Message-ID: Date: Mon, 29 Jul 2019 13:19:41 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190717080621.40424-9-yanaijie@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 17/07/2019 à 10:06, Jason Yan a écrit : > The original kernel still exists in the memory, clear it now. > > Signed-off-by: Jason Yan > Cc: Diana Craciun > Cc: Michael Ellerman > Cc: Christophe Leroy > Cc: Benjamin Herrenschmidt > Cc: Paul Mackerras > Cc: Nicholas Piggin > Cc: Kees Cook > --- > arch/powerpc/kernel/kaslr_booke.c | 11 +++++++++++ > arch/powerpc/mm/mmu_decl.h | 2 ++ > arch/powerpc/mm/nohash/fsl_booke.c | 1 + > 3 files changed, 14 insertions(+) > > diff --git a/arch/powerpc/kernel/kaslr_booke.c b/arch/powerpc/kernel/kaslr_booke.c > index 90357f4bd313..00339c05879f 100644 > --- a/arch/powerpc/kernel/kaslr_booke.c > +++ b/arch/powerpc/kernel/kaslr_booke.c > @@ -412,3 +412,14 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size) > > reloc_kernel_entry(dt_ptr, kimage_vaddr); > } > + > +void __init kaslr_second_init(void) > +{ > + /* If randomized, clear the original kernel */ > + if (kimage_vaddr != KERNELBASE) { > + unsigned long kernel_sz; > + > + kernel_sz = (unsigned long)_end - kimage_vaddr; > + memset((void *)KERNELBASE, 0, kernel_sz); Why are we clearing ? Is that just to tidy up or is it of security importance ? If so, maybe memzero_explicit() should be used instead ? > + } > +} > diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h > index 754ae1e69f92..9912ee598f9b 100644 > --- a/arch/powerpc/mm/mmu_decl.h > +++ b/arch/powerpc/mm/mmu_decl.h > @@ -150,8 +150,10 @@ extern void loadcam_multi(int first_idx, int num, int tmp_idx); > > #ifdef CONFIG_RANDOMIZE_BASE > extern void kaslr_early_init(void *dt_ptr, phys_addr_t size); > +extern void kaslr_second_init(void); No new 'extern' please. > #else > static inline void kaslr_early_init(void *dt_ptr, phys_addr_t size) {} > +static inline void kaslr_second_init(void) {} > #endif > > struct tlbcam { > diff --git a/arch/powerpc/mm/nohash/fsl_booke.c b/arch/powerpc/mm/nohash/fsl_booke.c > index 8d25a8dc965f..fa5a87f5c08e 100644 > --- a/arch/powerpc/mm/nohash/fsl_booke.c > +++ b/arch/powerpc/mm/nohash/fsl_booke.c > @@ -269,6 +269,7 @@ notrace void __init relocate_init(u64 dt_ptr, phys_addr_t start) > kernstart_addr = start; > if (is_second_reloc) { > virt_phys_offset = PAGE_OFFSET - memstart_addr; > + kaslr_second_init(); > return; > } > > Christophe