From patchwork Mon Jun 22 09:27:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 11617325 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 BD4B790 for ; Mon, 22 Jun 2020 09:27:44 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id CE74F20708 for ; Mon, 22 Jun 2020 09:27:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="bE16+dF6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CE74F20708 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-19031-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 14281 invoked by uid 550); 22 Jun 2020 09:27:41 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 14246 invoked from network); 22 Jun 2020 09:27:40 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592818048; bh=hWYKPFE9P3J3avt6bqZOYDK5HSShSgcf4lckraPXxZA=; h=From:To:Cc:Subject:Date:From; b=bE16+dF6SMSB5UO6GsVEiN6JX0rN2w/xk+OGYKNTJUb+jGdZHEf7uhLnvFNC8fgn5 Mr55iwAYSjwONJdCYnZn47MA3E/cI6HCCIsD4uAI8lk2WI/oUkrLWVdRioBvc3fBJv WTFEQKNTOlPW3mjJXXTFlE0tK5F/mPg4jxf13T/c= 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: [RFC PATCH] arm64/acpi: disallow AML memory opregions to access kernel memory Date: Mon, 22 Jun 2020 11:27:19 +0200 Message-Id: <20200622092719.1380968-1-ardb@kernel.org> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 ACPI provides support for SystemMemory opregions, to allow AML methods to access MMIO registers of, e.g., GPIO controllers, or access reserved regions of memory that are owned by the firmware. Currently, we also permit AML methods to access 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. So close the door on this, and simply reject AML remapping requests for any memory that has a valid mapping in the linear region. Reported-by: Jason A. Donenfeld Signed-off-by: Ard Biesheuvel --- arch/arm64/include/asm/acpi.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h index a45366c3909b..18dcef4e6764 100644 --- a/arch/arm64/include/asm/acpi.h +++ b/arch/arm64/include/asm/acpi.h @@ -50,9 +50,9 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr); static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size) { - /* For normal memory we already have a cacheable mapping. */ + /* Don't allow access to kernel memory from AML code */ if (memblock_is_map_memory(phys)) - return (void __iomem *)__phys_to_virt(phys); + return NULL; /* * We should still honor the memory's attribute here because