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=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, T_DKIMWL_WL_HIGH,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 2A797C43219 for ; Thu, 2 May 2019 15:48:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED152205C9 for ; Thu, 2 May 2019 15:48:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556812136; bh=xEwRVn6vW+YzMDRZ0xmL2n1BTiwlSjzDzU4hfBMfsfY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=snElPaAfeHv1jP1zvjfVjBHqtOV0Y5dyU/nCrYBQVTEkpoNkzGGMeuIIiyWnena+8 mP9Tcy04z8ICP394yk24Ie3hWt/H6P5bDjK95AHyLF4pK5XoYaodLYTWYl6cENfQz2 9mndVwopMOYH9kXav9TWjK7aUVPF5z7IbuBBRhWQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727348AbfEBPsz (ORCPT ); Thu, 2 May 2019 11:48:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:38504 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726809AbfEBPW6 (ORCPT ); Thu, 2 May 2019 11:22:58 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9FAF220C01; Thu, 2 May 2019 15:22:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556810577; bh=xEwRVn6vW+YzMDRZ0xmL2n1BTiwlSjzDzU4hfBMfsfY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dL3eAgAwngHPuZY+5oEZ8RhCFph5V69Oy926PDModq7Z2NGhV3FV8kWFcbpK0cP/r 7wzZaj3IeRfbQ9Hn6H/1+lUQVxDGHI33RBtEKSaa6ebxfV+GrGxL85ro7SRpme/ZwH /NY4Eo0dTk9OgjUlaRDV+eEJmkZgO0UDAgfIshTk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Auger , Peter Xu , Cornelia Huck , Alex Williamson , Guenter Roeck Subject: [PATCH 4.9 32/32] vfio/type1: Limit DMA mappings per container Date: Thu, 2 May 2019 17:21:18 +0200 Message-Id: <20190502143323.641847384@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190502143314.649935114@linuxfoundation.org> References: <20190502143314.649935114@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 commit 492855939bdb59c6f947b0b5b44af9ad82b7e38c upstream. 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 [groeck: Adjust for missing upstream commit] Signed-off-by: Guenter Roeck Signed-off-by: Greg Kroah-Hartman --- drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -53,10 +53,16 @@ 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 mutex lock; struct rb_root dma_list; + unsigned int dma_avail; bool v2; bool nesting; }; @@ -384,6 +390,7 @@ static void vfio_remove_dma(struct vfio_ vfio_unmap_unpin(iommu, dma); vfio_unlink_dma(iommu, dma); kfree(dma); + iommu->dma_avail++; } static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu) @@ -584,12 +591,18 @@ static int vfio_dma_do_map(struct vfio_i return -EEXIST; } + if (!iommu->dma_avail) { + mutex_unlock(&iommu->lock); + return -ENOSPC; + } + dma = kzalloc(sizeof(*dma), GFP_KERNEL); if (!dma) { mutex_unlock(&iommu->lock); return -ENOMEM; } + iommu->dma_avail--; dma->iova = iova; dma->vaddr = vaddr; dma->prot = prot; @@ -905,6 +918,7 @@ static void *vfio_iommu_type1_open(unsig INIT_LIST_HEAD(&iommu->domain_list); iommu->dma_list = RB_ROOT; + iommu->dma_avail = dma_entry_limit; mutex_init(&iommu->lock); return iommu;