From patchwork Fri Jun 26 15:58:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 11627917 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F309292A for ; Fri, 26 Jun 2020 15:58:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D394520773 for ; Fri, 26 Jun 2020 15:58:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593187125; bh=MI1bCIGMLcKccd2dmrayi3mwq6PLyLqFmsxPhzVVj+o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=HvG/BWUGexeejllKdvKq9pIu8aYjmxMYeKhTVV3rqLvOf5o4mCxfc0Ss3Qkqa1Kbs UiR7bu4ofNDQzNgdJE4ZdOR/8oriMgJnF93Fapajofarw8YkBK62Gv4UO12Khd48R0 5+YtSSBlga9GeJZztYyP0bUt9dOzoCOJiLfDvwyc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726026AbgFZP6p (ORCPT ); Fri, 26 Jun 2020 11:58:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:48964 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725958AbgFZP6p (ORCPT ); Fri, 26 Jun 2020 11:58:45 -0400 Received: from dogfood.home (lfbn-nic-1-188-42.w2-15.abo.wanadoo.fr [2.15.37.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6B9D82080C; Fri, 26 Jun 2020 15:58:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593187125; bh=MI1bCIGMLcKccd2dmrayi3mwq6PLyLqFmsxPhzVVj+o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pMTRSoP0LXtmeOSgiI76477HiCGpazaJWj4NOXf4jg37wdu7QJRO+hgH7/lbWlegp YbMVEvycZyfYFIw7lvXVRybyHe8zWKkHfI1tp0NnY6Ii7+0F1yeppV9UA9SqboJnmG d43IUvvLg9Bbk9CBd3EtE1y9ClPj/ONI/O8B3hsw= From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: linux-acpi@vger.kernel.org, will@kernel.org, catalin.marinas@arm.com, lorenzo.pieralisi@arm.com, sudeep.holla@arm.com, kernel-hardening@lists.openwall.com, Ard Biesheuvel Subject: [PATCH v3 2/2] arm64/acpi: disallow writeable AML opregion mapping for EFI code regions Date: Fri, 26 Jun 2020 17:58:32 +0200 Message-Id: <20200626155832.2323789-3-ardb@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200626155832.2323789-1-ardb@kernel.org> References: <20200626155832.2323789-1-ardb@kernel.org> MIME-Version: 1.0 Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org Given that the contents of EFI runtime code and data regions are provided by the firmware, as well as the DSDT, it is not unimaginable that AML code exists today that accesses EFI runtime code regions using a SystemMemory OpRegion. There is nothing fundamentally wrong with that, but since we take great care to ensure that executable code is never mapped writeable and executable at the same time, we should not permit AML to create writable mapping. Signed-off-by: Ard Biesheuvel --- arch/arm64/kernel/acpi.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index 01b861e225b0..455966401102 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -301,6 +301,15 @@ void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size) pr_warn(FW_BUG "requested region covers kernel memory @ %pa\n", &phys); return NULL; + case EFI_RUNTIME_SERVICES_CODE: + /* + * This would be unusual, but not problematic per se, + * as long as we take care not to create a writable + * mapping for executable code. + */ + prot = PAGE_KERNEL_RO; + break; + case EFI_ACPI_RECLAIM_MEMORY: /* * ACPI reclaim memory is used to pass firmware tables