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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 7C836C43387 for ; Wed, 16 Jan 2019 11:15:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4034220859 for ; Wed, 16 Jan 2019 11:15:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="LH36R7JF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732445AbfAPLPO (ORCPT ); Wed, 16 Jan 2019 06:15:14 -0500 Received: from mail.skyhub.de ([5.9.137.197]:49710 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728612AbfAPLPO (ORCPT ); Wed, 16 Jan 2019 06:15:14 -0500 Received: from zn.tnic (p200300EC2BC98A0074F02E32486DBF81.dip0.t-ipconnect.de [IPv6:2003:ec:2bc9:8a00:74f0:2e32:486d:bf81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id E977C1EC0570; Wed, 16 Jan 2019 12:15:12 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1547637313; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=VTQcpgdPysbG/e4v7TklNTVNwYJfHF4P/ABZxargYos=; b=LH36R7JFK76zT08fTP1mEGzGseKZ2wUkEP0ITuOoWWovdrnzUlddrHsIhZbD2mh9VdVfy2 ljy+rS54kFO8Dzkl5Dv/sI8pWWbUWpD6nPxggZf6Z83tEpGcP+v0we4BxEjcSXgP1Gr0// bQE0bB50m9ZYm7QiudqUao2XSVBcBcg= Date: Wed, 16 Jan 2019 12:15:07 +0100 From: Borislav Petkov To: Chao Fan Cc: linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, keescook@chromium.org, bhe@redhat.com, msys.mizuma@gmail.com, indou.takao@jp.fujitsu.com, caoj.fnst@cn.fujitsu.com Subject: Re: [PATCH v15 6/6] x86/boot/KASLR: Limit KASLR to extracting kernel in immovable memory Message-ID: <20190116111507.GD15409@zn.tnic> References: <20190107032243.25324-1-fanc.fnst@cn.fujitsu.com> <20190107032243.25324-7-fanc.fnst@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190107032243.25324-7-fanc.fnst@cn.fujitsu.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 07, 2019 at 11:22:43AM +0800, Chao Fan wrote: > KASLR may randomly choose some positions which are located in movable > memory regions. It will break memory hotplug feature and make the > movable memory chosen by KASLR can't be removed. > > The solution is to limit KASLR to choose memory regions in immovable > node according to SRAT tables. > When CONFIG_EARLY_SRAT_PARSE is enabled, walk through SRAT to get the > information of immovable memory so that KASLR knows where should be > chosen for randomization. > > Rename process_mem_region() as __process_mem_region() and name new > function as process_mem_region(). The commit message doesn't need to contain *what* you're doing in the patch. > > Signed-off-by: Chao Fan > --- > arch/x86/boot/compressed/kaslr.c | 79 +++++++++++++++++++++++++++----- > 1 file changed, 68 insertions(+), 11 deletions(-) > > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c > index b251572e77af..7dbec6910203 100644 > --- a/arch/x86/boot/compressed/kaslr.c > +++ b/arch/x86/boot/compressed/kaslr.c > @@ -97,6 +97,15 @@ static bool memmap_too_large; > /* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */ > static unsigned long long mem_limit = ULLONG_MAX; > > +#ifdef CONFIG_EARLY_SRAT_PARSE > +/* > + * Information of immovable memory regions. > + * Max amount of memory regions is MAX_NUMNODES*2, so need such array > + * to place immovable memory regions if all of the memory is immovable. > + */ Why is that comment repeated here? > +extern struct mem_vector immovable_mem[MAX_NUMNODES*2]; > +#endif > + > > enum mem_avoid_index { > MEM_AVOID_ZO_RANGE = 0, > @@ -413,6 +422,9 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size, > /* Mark the memmap regions we need to avoid */ > handle_mem_options(); > > + /* Mark the immovable regions we need to choose */ > + get_immovable_mem(); get != mark. Which should tell you that the function name needs changing. Also, this function is void and it could very well return num_immovable_mem and num_immovable_mem can be a static variable in kaslr.c instead of sloppily adding yet another global one. > + > #ifdef CONFIG_X86_VERBOSE_BOOTUP > /* Make sure video RAM can be used. */ > add_identity_map(0, PMD_SIZE); > @@ -568,9 +580,9 @@ static unsigned long slots_fetch_random(void) > return 0; > } > > -static void process_mem_region(struct mem_vector *entry, > - unsigned long minimum, > - unsigned long image_size) > +static void __process_mem_region(struct mem_vector *entry, > + unsigned long minimum, > + unsigned long image_size) > { > struct mem_vector region, overlap; > unsigned long start_orig, end; > @@ -646,6 +658,57 @@ static void process_mem_region(struct mem_vector *entry, > } > } > > +static bool process_mem_region(struct mem_vector *region, > + unsigned long long minimum, > + unsigned long long image_size) > +{ > + int i; > + /* > + * If no immovable memory found, or MEMORY_HOTREMOVE disabled, > + * walk all the regions, so use region directly. > + */ > + if (!num_immovable_mem) { > + __process_mem_region(region, minimum, image_size); > + > + if (slot_area_index == MAX_SLOT_AREA) { > + debug_putstr("Aborted e820/efi memmap scan (slot_areas full)!\n"); > + return 1; > + } > + return 0; > + } > + > +#ifdef CONFIG_EARLY_SRAT_PARSE > + /* > + * If immovable memory found, filter the intersection between > + * immovable memory and region to __process_mem_region(). > + * Otherwise, go on old code. > + */ > + for (i = 0; i < num_immovable_mem; i++) { > + unsigned long long start, end, entry_end, region_end; > + struct mem_vector entry; > + > + if (!mem_overlaps(region, &immovable_mem[i])) > + continue; > + > + start = immovable_mem[i].start; > + end = start + immovable_mem[i].size; > + region_end = region->start + region->size; > + > + entry.start = clamp(region->start, start, end); > + entry_end = clamp(region_end, start, end); > + entry.size = entry_end - entry.start; > + > + __process_mem_region(&entry, minimum, image_size); > + > + if (slot_area_index == MAX_SLOT_AREA) { > + debug_putstr("Aborted e820/efi memmap scan (slot_areas full)!\n"); Change this error message a bit to differ from the above for easier debugging. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.