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 Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DA443C433F5 for ; Fri, 17 Dec 2021 06:41:54 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 95DE240B51; Fri, 17 Dec 2021 06:41:54 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id dw7Jm9ecZhd3; Fri, 17 Dec 2021 06:41:53 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp2.osuosl.org (Postfix) with ESMTPS id 413EA40B66; Fri, 17 Dec 2021 06:41:53 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 051F4C002F; Fri, 17 Dec 2021 06:41:53 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [IPv6:2605:bc80:3010::137]) by lists.linuxfoundation.org (Postfix) with ESMTP id E24BBC0012 for ; Fri, 17 Dec 2021 06:41:51 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id DAD2441653 for ; Fri, 17 Dec 2021 06:41:51 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id lKPvH9vZD4nY for ; Fri, 17 Dec 2021 06:41:51 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by smtp4.osuosl.org (Postfix) with ESMTPS id 2002141602 for ; Fri, 17 Dec 2021 06:41:50 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10200"; a="238436322" X-IronPort-AV: E=Sophos;i="5.88,213,1635231600"; d="scan'208";a="238436322" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Dec 2021 22:41:50 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,213,1635231600"; d="scan'208";a="506653245" Received: from allen-box.sh.intel.com (HELO [10.239.159.118]) ([10.239.159.118]) by orsmga007.jf.intel.com with ESMTP; 16 Dec 2021 22:41:43 -0800 Subject: Re: [PATCH v3 00/18] Fix BUG_ON in vfio_iommu_group_notifier() To: Greg Kroah-Hartman , Joerg Roedel , Alex Williamson , Bjorn Helgaas , Jason Gunthorpe , Christoph Hellwig , Kevin Tian , Ashok Raj References: <20211206015903.88687-1-baolu.lu@linux.intel.com> From: Lu Baolu Message-ID: Date: Fri, 17 Dec 2021 14:41:24 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211206015903.88687-1-baolu.lu@linux.intel.com> Content-Language: en-US Cc: kvm@vger.kernel.org, rafael@kernel.org, David Airlie , linux-pci@vger.kernel.org, Thierry Reding , Diana Craciun , Dmitry Osipenko , Will Deacon , Stuart Yoder , Jonathan Hunter , Chaitanya Kulkarni , Dan Williams , Cornelia Huck , linux-kernel@vger.kernel.org, Li Yang , iommu@lists.linux-foundation.org, Jacob jun Pan , Daniel Vetter , Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 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" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 12/6/21 9:58 AM, Lu Baolu wrote: > Hi folks, > > The iommu group is the minimal isolation boundary for DMA. Devices in > a group can access each other's MMIO registers via peer to peer DMA > and also need share the same I/O address space. > > Once the I/O address space is assigned to user control it is no longer > available to the dma_map* API, which effectively makes the DMA API > non-working. > > Second, userspace can use DMA initiated by a device that it controls > to access the MMIO spaces of other devices in the group. This allows > userspace to indirectly attack any kernel owned device and it's driver. > > Therefore groups must either be entirely under kernel control or > userspace control, never a mixture. Unfortunately some systems have > problems with the granularity of groups and there are a couple of > important exceptions: > > - pci_stub allows the admin to block driver binding on a device and > make it permanently shared with userspace. Since PCI stub does not > do DMA it is safe, however the admin must understand that using > pci_stub allows userspace to attack whatever device it was bound > it. > > - PCI bridges are sometimes included in groups. Typically PCI bridges > do not use DMA, and generally do not have MMIO regions. > > Generally any device that does not have any MMIO registers is a > possible candidate for an exception. > > Currently vfio adopts a workaround to detect violations of the above > restrictions by monitoring the driver core BOUND event, and hardwiring > the above exceptions. Since there is no way for vfio to reject driver > binding at this point, BUG_ON() is triggered if a violation is > captured (kernel driver BOUND event on a group which already has some > devices assigned to userspace). Aside from the bad user experience > this opens a way for root userspace to crash the kernel, even in high > integrity configurations, by manipulating the module binding and > triggering the BUG_ON. > > This series solves this problem by making the user/kernel ownership a > core concept at the IOMMU layer. The driver core enforces kernel > ownership while drivers are bound and violations now result in a error > codes during probe, not BUG_ON failures. > > Patch partitions: > [PATCH 1-9]: Detect DMA ownership conflicts during driver binding; > [PATCH 10-13]: Add security context management for assigned devices; > [PATCH 14-18]: Various cleanups. > > This is part one of three initial series for IOMMUFD: > * Move IOMMU Group security into the iommu layer > - Generic IOMMUFD implementation > - VFIO ability to consume IOMMUFD Thank you very much for reviewing my series. The v4 of this series has been posted here: https://lore.kernel.org/linux-iommu/20211217063708.1740334-1-baolu.lu@linux.intel.com/ Best regards, baolu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu