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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 C4F5CC31E44 for ; Wed, 12 Jun 2019 03:15:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A5D0A2086D for ; Wed, 12 Jun 2019 03:15:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437115AbfFLDPi (ORCPT ); Tue, 11 Jun 2019 23:15:38 -0400 Received: from mga07.intel.com ([134.134.136.100]:29460 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406820AbfFLDPi (ORCPT ); Tue, 11 Jun 2019 23:15:38 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jun 2019 20:15:38 -0700 X-ExtLoop1: 1 Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by orsmga004.jf.intel.com with ESMTP; 11 Jun 2019 20:15:32 -0700 Cc: baolu.lu@linux.intel.com, David Woodhouse , Joerg Roedel , Bjorn Helgaas , Christoph Hellwig , ashok.raj@intel.com, jacob.jun.pan@intel.com, alan.cox@intel.com, kevin.tian@intel.com, mika.westerberg@linux.intel.com, Ingo Molnar , Greg Kroah-Hartman , pengfei.xu@intel.com, Marek Szyprowski , Robin Murphy , Jonathan Corbet , Boris Ostrovsky , Juergen Gross , Stefano Stabellini , Steven Rostedt , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 3/9] swiotlb: Zero out bounce buffer for untrusted device To: Konrad Rzeszutek Wilk References: <20190603011620.31999-1-baolu.lu@linux.intel.com> <20190603011620.31999-4-baolu.lu@linux.intel.com> <20190610154553.GT28796@char.us.oracle.com> <20190612010518.GB22479@char.us.oracle.com> From: Lu Baolu Message-ID: <8ad77caa-3245-4d06-314d-c4a92aa0f2ac@linux.intel.com> Date: Wed, 12 Jun 2019 11:08:24 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190612010518.GB22479@char.us.oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 6/12/19 9:05 AM, Konrad Rzeszutek Wilk wrote: > On Wed, Jun 12, 2019 at 08:43:40AM +0800, Lu Baolu wrote: >> Hi Konrad, >> >> Thanks a lot for your reviewing. >> >> On 6/10/19 11:45 PM, Konrad Rzeszutek Wilk wrote: >>> On Mon, Jun 03, 2019 at 09:16:14AM +0800, Lu Baolu wrote: >>>> This is necessary to avoid exposing valid kernel data to any >>>> milicious device. >>> >>> malicious >> >> Yes, thanks. >> >>> >>>> >>>> Suggested-by: Christoph Hellwig >>>> Signed-off-by: Lu Baolu >>>> --- >>>> kernel/dma/swiotlb.c | 6 ++++++ >>>> 1 file changed, 6 insertions(+) >>>> >>>> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c >>>> index f956f785645a..ed41eb7f6131 100644 >>>> --- a/kernel/dma/swiotlb.c >>>> +++ b/kernel/dma/swiotlb.c >>>> @@ -35,6 +35,7 @@ >>>> #include >>>> #include >>>> #include >>>> +#include >>>> #ifdef CONFIG_DEBUG_FS >>>> #include >>>> #endif >>>> @@ -560,6 +561,11 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, >>>> */ >>>> for (i = 0; i < nslots; i++) >>>> io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT); >>>> + >>>> + /* Zero out the bounce buffer if the consumer is untrusted. */ >>>> + if (dev_is_untrusted(hwdev)) >>>> + memset(phys_to_virt(tlb_addr), 0, alloc_size); >>> >>> What if the alloc_size is less than a PAGE? Should this at least have ALIGN or such? >> >> It's the consumer (iommu subsystem) who requires this to be page >> aligned. For swiotlb, it just clears out all data in the allocated >> bounce buffer. > > I am thinking that the if you don't memset the full page the malicious hardware could read stale date from the rest of the page > that hasn't been cleared? Yes. My point is that this should be guaranteed by the bounce page implementation in iommu. Best regards, Baolu > >> >> Best regards, >> Baolu >> >>> >>>> + >>>> if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && >>>> (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)) >>>> swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE); >>>> -- >>>> 2.17.1 >>>> >>> > 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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 DF1E8C31E44 for ; Wed, 12 Jun 2019 03:17:40 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B2D292082C for ; Wed, 12 Jun 2019 03:17:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B2D292082C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 81D5614F8; Wed, 12 Jun 2019 03:17:40 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 4A3EE14F5 for ; Wed, 12 Jun 2019 03:15:39 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id C6B6B79 for ; Wed, 12 Jun 2019 03:15:38 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jun 2019 20:15:38 -0700 X-ExtLoop1: 1 Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by orsmga004.jf.intel.com with ESMTP; 11 Jun 2019 20:15:32 -0700 Subject: Re: [PATCH v4 3/9] swiotlb: Zero out bounce buffer for untrusted device To: Konrad Rzeszutek Wilk References: <20190603011620.31999-1-baolu.lu@linux.intel.com> <20190603011620.31999-4-baolu.lu@linux.intel.com> <20190610154553.GT28796@char.us.oracle.com> <20190612010518.GB22479@char.us.oracle.com> From: Lu Baolu Message-ID: <8ad77caa-3245-4d06-314d-c4a92aa0f2ac@linux.intel.com> Date: Wed, 12 Jun 2019 11:08:24 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190612010518.GB22479@char.us.oracle.com> Content-Language: en-US Cc: alan.cox@intel.com, Christoph Hellwig , Stefano Stabellini , ashok.raj@intel.com, Jonathan Corbet , pengfei.xu@intel.com, Ingo Molnar , David Woodhouse , kevin.tian@intel.com, Steven Rostedt , Bjorn Helgaas , Boris Ostrovsky , mika.westerberg@linux.intel.com, Juergen Gross , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, jacob.jun.pan@intel.com, Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org Hi, On 6/12/19 9:05 AM, Konrad Rzeszutek Wilk wrote: > On Wed, Jun 12, 2019 at 08:43:40AM +0800, Lu Baolu wrote: >> Hi Konrad, >> >> Thanks a lot for your reviewing. >> >> On 6/10/19 11:45 PM, Konrad Rzeszutek Wilk wrote: >>> On Mon, Jun 03, 2019 at 09:16:14AM +0800, Lu Baolu wrote: >>>> This is necessary to avoid exposing valid kernel data to any >>>> milicious device. >>> >>> malicious >> >> Yes, thanks. >> >>> >>>> >>>> Suggested-by: Christoph Hellwig >>>> Signed-off-by: Lu Baolu >>>> --- >>>> kernel/dma/swiotlb.c | 6 ++++++ >>>> 1 file changed, 6 insertions(+) >>>> >>>> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c >>>> index f956f785645a..ed41eb7f6131 100644 >>>> --- a/kernel/dma/swiotlb.c >>>> +++ b/kernel/dma/swiotlb.c >>>> @@ -35,6 +35,7 @@ >>>> #include >>>> #include >>>> #include >>>> +#include >>>> #ifdef CONFIG_DEBUG_FS >>>> #include >>>> #endif >>>> @@ -560,6 +561,11 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, >>>> */ >>>> for (i = 0; i < nslots; i++) >>>> io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT); >>>> + >>>> + /* Zero out the bounce buffer if the consumer is untrusted. */ >>>> + if (dev_is_untrusted(hwdev)) >>>> + memset(phys_to_virt(tlb_addr), 0, alloc_size); >>> >>> What if the alloc_size is less than a PAGE? Should this at least have ALIGN or such? >> >> It's the consumer (iommu subsystem) who requires this to be page >> aligned. For swiotlb, it just clears out all data in the allocated >> bounce buffer. > > I am thinking that the if you don't memset the full page the malicious hardware could read stale date from the rest of the page > that hasn't been cleared? Yes. My point is that this should be guaranteed by the bounce page implementation in iommu. Best regards, Baolu > >> >> Best regards, >> Baolu >> >>> >>>> + >>>> if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && >>>> (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)) >>>> swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE); >>>> -- >>>> 2.17.1 >>>> >>> > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu