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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT 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 74BE1C10F11 for ; Wed, 24 Apr 2019 14:38:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 41D7E218FE for ; Wed, 24 Apr 2019 14:38:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556116709; bh=o0GTP6ujbkkuVyeHE7SrZp6FfvHjpIxR0turRfY0PA4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZbYUL/wLUNmxIXRoIk0xiiLpgPDGu2ObJoBKllzLssLaTFj1tnZcVcMaCfJ3J8UqB vvbl9bY1gCnR2DmqLSPXvnlKFwp2dGXufSejMjF37mNFHhDSILyhDnzGPPhRQRAMPR RtQbAoT1lJX07CDE7fCtIExiR86GagZMwu20DIHo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731431AbfDXOi1 (ORCPT ); Wed, 24 Apr 2019 10:38:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:39152 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731341AbfDXOfV (ORCPT ); Wed, 24 Apr 2019 10:35:21 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 27C712089F; Wed, 24 Apr 2019 14:35:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556116520; bh=o0GTP6ujbkkuVyeHE7SrZp6FfvHjpIxR0turRfY0PA4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iASq/sOvnOkX+CsDHVGFd1w6/TiE4PdCvLMxwUsLI7Q5WAMONdbcdZFiGlizeRPMS qo9173w5oRLzOQNgkKhrcYvcyWO+UbaRaaRcfdbYnx8Fh2zxILrCUW18jDP0MjhOxD kFcmtDtYj9x/ZfER8BaVl/EUHK+oMvs0jpcanzKY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Alex Williamson , Sasha Levin , kvm@vger.kernel.org Subject: [PATCH AUTOSEL 5.0 40/66] vfio/type1: Limit DMA mappings per container Date: Wed, 24 Apr 2019 10:33:14 -0400 Message-Id: <20190424143341.27665-40-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190424143341.27665-1-sashal@kernel.org> References: <20190424143341.27665-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alex Williamson [ Upstream commit 492855939bdb59c6f947b0b5b44af9ad82b7e38c ] Memory backed DMA mappings are accounted against a user's locked memory limit, including multiple mappings of the same memory. This accounting bounds the number of such mappings that a user can create. However, DMA mappings that are not backed by memory, such as DMA mappings of device MMIO via mmaps, do not make use of page pinning and therefore do not count against the user's locked memory limit. These mappings still consume memory, but the memory is not well associated to the process for the purpose of oom killing a task. To add bounding on this use case, we introduce a limit to the total number of concurrent DMA mappings that a user is allowed to create. This limit is exposed as a tunable module option where the default value of 64K is expected to be well in excess of any reasonable use case (a large virtual machine configuration would typically only make use of tens of concurrent mappings). This fixes CVE-2019-3882. Reviewed-by: Eric Auger Tested-by: Eric Auger Reviewed-by: Peter Xu Reviewed-by: Cornelia Huck Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin (Microsoft) --- drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 73652e21efec..d0f731c9920a 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -58,12 +58,18 @@ module_param_named(disable_hugepages, MODULE_PARM_DESC(disable_hugepages, "Disable VFIO IOMMU support for IOMMU hugepages."); +static unsigned int dma_entry_limit __read_mostly = U16_MAX; +module_param_named(dma_entry_limit, dma_entry_limit, uint, 0644); +MODULE_PARM_DESC(dma_entry_limit, + "Maximum number of user DMA mappings per container (65535)."); + struct vfio_iommu { struct list_head domain_list; struct vfio_domain *external_domain; /* domain for external user */ struct mutex lock; struct rb_root dma_list; struct blocking_notifier_head notifier; + unsigned int dma_avail; bool v2; bool nesting; }; @@ -836,6 +842,7 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma) vfio_unlink_dma(iommu, dma); put_task_struct(dma->task); kfree(dma); + iommu->dma_avail++; } static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu) @@ -1081,12 +1088,18 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu, goto out_unlock; } + if (!iommu->dma_avail) { + ret = -ENOSPC; + goto out_unlock; + } + dma = kzalloc(sizeof(*dma), GFP_KERNEL); if (!dma) { ret = -ENOMEM; goto out_unlock; } + iommu->dma_avail--; dma->iova = iova; dma->vaddr = vaddr; dma->prot = prot; @@ -1583,6 +1596,7 @@ static void *vfio_iommu_type1_open(unsigned long arg) INIT_LIST_HEAD(&iommu->domain_list); iommu->dma_list = RB_ROOT; + iommu->dma_avail = dma_entry_limit; mutex_init(&iommu->lock); BLOCKING_INIT_NOTIFIER_HEAD(&iommu->notifier); -- 2.19.1