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=-6.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT 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 DF4ECC43219 for ; Tue, 30 Apr 2019 11:41:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AE37421670 for ; Tue, 30 Apr 2019 11:41:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556624505; bh=T1JUppLhCQLKwZ/KD4FnKGXmGHHOZxgeuKsHLw4zNpM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=sURNP5vTEadGlrshr2Ku6iEqP2+x8tvyGjchk3rVrcFwcqUBMwHy8COS7s9xor9hX T6fs6ryL6l4dNX4mio0WUYqvMK3Of6OgU1LR+T8UX2Qhn78qjiF49zcr1R7yNAyK82 pb7KkDmjNAOdOcK7m72nj6bLc6Ul6xCYm0I9Lbaw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729026AbfD3Llo (ORCPT ); Tue, 30 Apr 2019 07:41:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:49598 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728152AbfD3Lll (ORCPT ); Tue, 30 Apr 2019 07:41:41 -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 14ABB21743; Tue, 30 Apr 2019 11:41:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556624499; bh=T1JUppLhCQLKwZ/KD4FnKGXmGHHOZxgeuKsHLw4zNpM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZIOP/87+xGUx4J5ox2zaGVUEQkd0U+wxObF/BWkW/EZ4UCPol3JA1CW2L/i1gYBxT 6RrEC2sTk2iXVsVhARJ8dAd+TY9jIetEvcCsPIlsOCVVkpIBuGidqDl2FTcweDZdcx j3UFIxogm1v9tAB6bOtP+DGb7Ato9vKpeff4L25k= 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 Subject: [PATCH 4.14 17/53] vfio/type1: Limit DMA mappings per container Date: Tue, 30 Apr 2019 13:38:24 +0200 Message-Id: <20190430113553.475108039@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190430113549.400132183@linuxfoundation.org> References: <20190430113549.400132183@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 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 @@ -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; }; @@ -732,6 +738,7 @@ static void vfio_remove_dma(struct vfio_ 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) @@ -1003,12 +1010,18 @@ static int vfio_dma_do_map(struct vfio_i 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; @@ -1504,6 +1517,7 @@ 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); BLOCKING_INIT_NOTIFIER_HEAD(&iommu->notifier);