From patchwork Fri Jun 26 15:58:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 11627915 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 50EC1912 for ; Fri, 26 Jun 2020 15:58:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35F6120773 for ; Fri, 26 Jun 2020 15:58:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593187124; bh=CLa/KzjkFuVB29ckXD65Yi/MPGSAfUM7uGj3uLRMd8c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=EsvbiSBgcGbY0ZNy12Vn4Gmdw/H4bE/2aar6nQUr0oH5s2FZGpcFmwWaSLUEFA6Z0 aCmpiEpgVqK0dtoe45d28vxR4sFaN2nIHm2mrRpR3d8UqcTJIddu37nYI0z98WhgV/ e8cgC23weh0V9biFbOnBTxgR97m3scB72p4tn92w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726383AbgFZP6n (ORCPT ); Fri, 26 Jun 2020 11:58:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:48886 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725958AbgFZP6n (ORCPT ); Fri, 26 Jun 2020 11:58:43 -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 44682207FC; Fri, 26 Jun 2020 15:58:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593187123; bh=CLa/KzjkFuVB29ckXD65Yi/MPGSAfUM7uGj3uLRMd8c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KvkqltL7W8QSPKTPhvffxK28GoCuvQLjCChN2Ds1Eul/Ijdz/A4oA+ajy5pKuK7Y8 94WMZjajjI56YrQyBi5rSRaIHerNWXXrIqyvkRgXalg3TIe97DBCQy1h6HDSOvm81N VK9Lnps++4YE0cPVnQn+7mDc69oGPUt/SuJo6i/s= 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 , "Jason A . Donenfeld" Subject: [PATCH v3 1/2] arm64/acpi: disallow AML memory opregions to access kernel memory Date: Fri, 26 Jun 2020 17:58:31 +0200 Message-Id: <20200626155832.2323789-2-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 AML uses SystemMemory opregions to allow AML handlers to access MMIO registers of, e.g., GPIO controllers, or access reserved regions of memory that are owned by the firmware. Currently, we also allow AML access to memory that is owned by the kernel and mapped via the linear region, which does not seem to be supported by a valid use case, and exposes the kernel's internal state to AML methods that may be buggy and exploitable. On arm64, ACPI support requires booting in EFI mode, and so we can cross reference the requested region against the EFI memory map, rather than just do a minimal check on the first page. So let's only permit regions to be remapped by the ACPI core if - they don't appear in the EFI memory map at all (which is the case for most MMIO), or - they are covered by a single region in the EFI memory map, which is not of a type that describes memory that is given to the kernel at boot. Reported-by: Jason A. Donenfeld Signed-off-by: Ard Biesheuvel Tested-by: Jonathan Cameron Reviewed-by: Jonathan Cameron --- arch/arm64/include/asm/acpi.h | 15 +---- arch/arm64/kernel/acpi.c | 66 ++++++++++++++++++++ 2 files changed, 67 insertions(+), 14 deletions(-) diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h index a45366c3909b..bd68e1b7f29f 100644 --- a/arch/arm64/include/asm/acpi.h +++ b/arch/arm64/include/asm/acpi.h @@ -47,20 +47,7 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr); /* ACPI table mapping after acpi_permanent_mmap is set */ -static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys, - acpi_size size) -{ - /* For normal memory we already have a cacheable mapping. */ - if (memblock_is_map_memory(phys)) - return (void __iomem *)__phys_to_virt(phys); - - /* - * We should still honor the memory's attribute here because - * crash dump kernel possibly excludes some ACPI (reclaim) - * regions from memblock list. - */ - return __ioremap(phys, size, __acpi_get_mem_attribute(phys)); -} +void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size); #define acpi_os_ioremap acpi_os_ioremap typedef u64 phys_cpuid_t; diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index a7586a4db142..01b861e225b0 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -261,6 +261,72 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr) return __pgprot(PROT_DEVICE_nGnRnE); } +void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size) +{ + efi_memory_desc_t *md, *region = NULL; + pgprot_t prot; + + if (WARN_ON_ONCE(!efi_enabled(EFI_MEMMAP))) + return NULL; + + for_each_efi_memory_desc(md) { + u64 end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT); + + if (phys < md->phys_addr || phys >= end) + continue; + + if (phys + size > end) { + pr_warn(FW_BUG "requested region covers multiple EFI memory regions\n"); + return NULL; + } + region = md; + break; + } + + /* + * It is fine for AML to remap regions that are not represented in the + * EFI memory map at all, as it only describes normal memory, and MMIO + * regions that require a virtual mapping to make them accessible to + * the EFI runtime services. + */ + prot = __pgprot(PROT_DEVICE_nGnRnE); + if (region) { + switch (region->type) { + case EFI_LOADER_CODE: + case EFI_LOADER_DATA: + case EFI_BOOT_SERVICES_CODE: + case EFI_BOOT_SERVICES_DATA: + case EFI_CONVENTIONAL_MEMORY: + case EFI_PERSISTENT_MEMORY: + pr_warn(FW_BUG "requested region covers kernel memory @ %pa\n", &phys); + return NULL; + + case EFI_ACPI_RECLAIM_MEMORY: + /* + * ACPI reclaim memory is used to pass firmware tables + * and other data that is intended for consumption by + * the OS only, which may decide it wants to reclaim + * that memory and use it for something else. We never + * do that, but we usually add it to the linear map + * anyway, in which case we should use the existing + * mapping. + */ + if (memblock_is_map_memory(phys)) + return (void __iomem *)__phys_to_virt(phys); + /* fall through */ + + default: + if (region->attribute & EFI_MEMORY_WB) + prot = PAGE_KERNEL; + else if (region->attribute & EFI_MEMORY_WT) + prot = __pgprot(PROT_NORMAL_WT); + else if (region->attribute & EFI_MEMORY_WC) + prot = __pgprot(PROT_NORMAL_NC); + } + } + return __ioremap(phys, size, prot); +} + /* * Claim Synchronous External Aborts as a firmware first notification. *