From patchwork Thu Nov 29 15:51:50 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mika Westerberg X-Patchwork-Id: 10704817 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 486B24B7E for ; Thu, 29 Nov 2018 15:52:18 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3A1E22F47D for ; Thu, 29 Nov 2018 15:52:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2E19E2F4C9; Thu, 29 Nov 2018 15:52:18 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B086A2F4B3 for ; Thu, 29 Nov 2018 15:52:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729202AbeK3C5t (ORCPT ); Thu, 29 Nov 2018 21:57:49 -0500 Received: from mga01.intel.com ([192.55.52.88]:45035 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729143AbeK3C5t (ORCPT ); Thu, 29 Nov 2018 21:57:49 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Nov 2018 07:52:00 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,295,1539673200"; d="scan'208";a="95793206" Received: from black.fi.intel.com ([10.237.72.28]) by orsmga006.jf.intel.com with ESMTP; 29 Nov 2018 07:51:54 -0800 Received: by black.fi.intel.com (Postfix, from userid 1001) id C3B80E7; Thu, 29 Nov 2018 17:51:53 +0200 (EET) From: Mika Westerberg To: iommu@lists.linux-foundation.org Cc: Joerg Roedel , David Woodhouse , Lu Baolu , Ashok Raj , Bjorn Helgaas , "Rafael J. Wysocki" , Jacob jun Pan , Andreas Noever , Michael Jamet , Yehezkel Bernat , Lukas Wunner , Christian Kellner , Mario.Limonciello@dell.com, Anthony Wong , Lorenzo Pieralisi , Christoph Hellwig , Alex Williamson , Mika Westerberg , linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/4] PCI / ACPI: Identify untrusted PCI devices Date: Thu, 29 Nov 2018 18:51:50 +0300 Message-Id: <20181129155153.35840-2-mika.westerberg@linux.intel.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181129155153.35840-1-mika.westerberg@linux.intel.com> References: <20181129155153.35840-1-mika.westerberg@linux.intel.com> MIME-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP A malicious PCI device may use DMA to attack the system. An external Thunderbolt port is a convenient point to attach such a device. The OS may use IOMMU to defend against DMA attacks. Recent BIOSes with Thunderbolt ports mark these externally facing root ports with this ACPI _DSD [1]: Name (_DSD, Package () { ToUUID ("efcc06cc-73ac-4bc3-bff0-76143807c389"), Package () { Package () {"ExternalFacingPort", 1}, Package () {"UID", 0 } } }) If we find such a root port, mark it and all its children as untrusted. The rest of the OS may use this information to enable DMA protection against malicious devices. For instance the device may be put behind an IOMMU to keep it from accessing memory outside of what the driver has allocated for it. While at it, add a comment on top of prp_guids array explaining the possible caveat resulting when these GUIDs are treated equivalent. [1] https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports#identifying-externally-exposed-pcie-root-ports Signed-off-by: Mika Westerberg Acked-by: Rafael J. Wysocki Acked-by: Bjorn Helgaas --- drivers/acpi/property.c | 11 +++++++++++ drivers/pci/pci-acpi.c | 19 +++++++++++++++++++ drivers/pci/probe.c | 15 +++++++++++++++ include/linux/pci.h | 8 ++++++++ 4 files changed, 53 insertions(+) diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c index 8c7c4583b52d..77abe0ec4043 100644 --- a/drivers/acpi/property.c +++ b/drivers/acpi/property.c @@ -24,6 +24,14 @@ static int acpi_data_get_property_array(const struct acpi_device_data *data, acpi_object_type type, const union acpi_object **obj); +/* + * The GUIDs here are made equivalent to each other in order to avoid extra + * complexity in the properties handling code, with the caveat that the + * kernel will accept certain combinations of GUID and properties that are + * not defined without a warning. For instance if any of the properties + * from different GUID appear in a property list of another, it will be + * accepted by the kernel. Firmware validation tools should catch these. + */ static const guid_t prp_guids[] = { /* ACPI _DSD device properties GUID: daffd814-6eba-4d8c-8a91-bc9bbf4aa301 */ GUID_INIT(0xdaffd814, 0x6eba, 0x4d8c, @@ -31,6 +39,9 @@ static const guid_t prp_guids[] = { /* Hotplug in D3 GUID: 6211e2c0-58a3-4af3-90e1-927a4e0c55a4 */ GUID_INIT(0x6211e2c0, 0x58a3, 0x4af3, 0x90, 0xe1, 0x92, 0x7a, 0x4e, 0x0c, 0x55, 0xa4), + /* External facing port GUID: efcc06cc-73ac-4bc3-bff0-76143807c389 */ + GUID_INIT(0xefcc06cc, 0x73ac, 0x4bc3, + 0xbf, 0xf0, 0x76, 0x14, 0x38, 0x07, 0xc3, 0x89), }; static const guid_t ads_guid = diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index 921db6f80340..e1949f7efd9c 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -789,6 +789,24 @@ static void pci_acpi_optimize_delay(struct pci_dev *pdev, ACPI_FREE(obj); } +static void pci_acpi_set_untrusted(struct pci_dev *dev) +{ + u8 val; + + if (pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT) + return; + if (device_property_read_u8(&dev->dev, "ExternalFacingPort", &val)) + return; + + /* + * These root ports expose PCIe (including DMA) outside of the + * system so make sure we treat them and everything behind as + * untrusted. + */ + if (val) + dev->untrusted = 1; +} + static void pci_acpi_setup(struct device *dev) { struct pci_dev *pci_dev = to_pci_dev(dev); @@ -798,6 +816,7 @@ static void pci_acpi_setup(struct device *dev) return; pci_acpi_optimize_delay(pci_dev, adev->handle); + pci_acpi_set_untrusted(pci_dev); pci_acpi_add_pm_notifier(adev, pci_dev); if (!adev->wakeup.flags.valid) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index b1c05b5054a0..257b9f6f2ebb 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1378,6 +1378,19 @@ static void set_pcie_thunderbolt(struct pci_dev *dev) } } +static void set_pcie_untrusted(struct pci_dev *dev) +{ + struct pci_dev *parent; + + /* + * If the upstream bridge is untrusted we treat this device + * untrusted as well. + */ + parent = pci_upstream_bridge(dev); + if (parent && parent->untrusted) + dev->untrusted = true; +} + /** * pci_ext_cfg_is_aliased - Is ext config space just an alias of std config? * @dev: PCI device @@ -1638,6 +1651,8 @@ int pci_setup_device(struct pci_dev *dev) /* Need to have dev->cfg_size ready */ set_pcie_thunderbolt(dev); + set_pcie_untrusted(dev); + /* "Unknown power state" */ dev->current_state = PCI_UNKNOWN; diff --git a/include/linux/pci.h b/include/linux/pci.h index 11c71c4ecf75..c786a2f27bee 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -396,6 +396,14 @@ struct pci_dev { unsigned int is_hotplug_bridge:1; unsigned int shpc_managed:1; /* SHPC owned by shpchp */ unsigned int is_thunderbolt:1; /* Thunderbolt controller */ + /* + * Devices marked being untrusted are the ones that can potentially + * execute DMA attacks and similar. They are typically connected + * through external ports such as Thunderbolt but not limited to + * that. When an IOMMU is enabled they should be getting full + * mappings to make sure they cannot access arbitrary memory. + */ + unsigned int untrusted:1; unsigned int __aer_firmware_first_valid:1; unsigned int __aer_firmware_first:1; unsigned int broken_intx_masking:1; /* INTx masking can't be used */ From patchwork Thu Nov 29 15:51:51 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mika Westerberg X-Patchwork-Id: 10704811 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C947917D5 for ; Thu, 29 Nov 2018 15:52:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BAC5A2F46C for ; Thu, 29 Nov 2018 15:52:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AEB012F488; Thu, 29 Nov 2018 15:52:10 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 263812F46C for ; Thu, 29 Nov 2018 15:52:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729257AbeK3C5w (ORCPT ); Thu, 29 Nov 2018 21:57:52 -0500 Received: from mga01.intel.com ([192.55.52.88]:45035 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729152AbeK3C5v (ORCPT ); Thu, 29 Nov 2018 21:57:51 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Nov 2018 07:52:00 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,295,1539673200"; d="scan'208";a="95793219" Received: from black.fi.intel.com ([10.237.72.28]) by orsmga006.jf.intel.com with ESMTP; 29 Nov 2018 07:51:54 -0800 Received: by black.fi.intel.com (Postfix, from userid 1001) id D645B1EE; Thu, 29 Nov 2018 17:51:53 +0200 (EET) From: Mika Westerberg To: iommu@lists.linux-foundation.org Cc: Joerg Roedel , David Woodhouse , Lu Baolu , Ashok Raj , Bjorn Helgaas , "Rafael J. Wysocki" , Jacob jun Pan , Andreas Noever , Michael Jamet , Yehezkel Bernat , Lukas Wunner , Christian Kellner , Mario.Limonciello@dell.com, Anthony Wong , Lorenzo Pieralisi , Christoph Hellwig , Alex Williamson , Mika Westerberg , linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 2/4] iommu/vt-d: Force IOMMU on for platform opt in hint Date: Thu, 29 Nov 2018 18:51:51 +0300 Message-Id: <20181129155153.35840-3-mika.westerberg@linux.intel.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181129155153.35840-1-mika.westerberg@linux.intel.com> References: <20181129155153.35840-1-mika.westerberg@linux.intel.com> MIME-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Lu Baolu Intel VT-d spec added a new DMA_CTRL_PLATFORM_OPT_IN_FLAG flag in DMAR ACPI table [1] for BIOS to report compliance about platform initiated DMA restricted to RMRR ranges when transferring control to the OS. This means that during OS boot, before it enables IOMMU none of the connected devices can bypass DMA protection for instance by overwriting the data structures used by the IOMMU. The OS also treats this as a hint that the IOMMU should be enabled to prevent DMA attacks from possible malicious devices. A use of this flag is Kernel DMA protection for Thunderbolt [2] which in practice means that IOMMU should be enabled for PCIe devices connected to the Thunderbolt ports. With IOMMU enabled for these devices, all DMA operations are limited in the range reserved for it, thus the DMA attacks are prevented. All these devices are enumerated in the PCI/PCIe module and marked with an untrusted flag. This forces IOMMU to be enabled if DMA_CTRL_PLATFORM_OPT_IN_FLAG is set in DMAR ACPI table and there are PCIe devices marked as untrusted in the system. This can be turned off by adding "intel_iommu=off" in the kernel command line, if any problems are found. [1] https://software.intel.com/sites/default/files/managed/c5/15/vt-directed-io-spec.pdf [2] https://docs.microsoft.com/en-us/windows/security/information-protection/kernel-dma-protection-for-thunderbolt Cc: Jacob Pan Cc: Sohil Mehta Signed-off-by: Lu Baolu Signed-off-by: Mika Westerberg Reviewed-by: Ashok Raj Reviewed-by: Joerg Roedel Acked-by: Joerg Roedel --- drivers/iommu/dmar.c | 25 +++++++++++++++++ drivers/iommu/intel-iommu.c | 53 +++++++++++++++++++++++++++++++++++-- include/linux/dmar.h | 8 ++++++ 3 files changed, 84 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c index d9c748b6f9e4..1edf2a251336 100644 --- a/drivers/iommu/dmar.c +++ b/drivers/iommu/dmar.c @@ -2042,3 +2042,28 @@ int dmar_device_remove(acpi_handle handle) { return dmar_device_hotplug(handle, false); } + +/* + * dmar_platform_optin - Is %DMA_CTRL_PLATFORM_OPT_IN_FLAG set in DMAR table + * + * Returns true if the platform has %DMA_CTRL_PLATFORM_OPT_IN_FLAG set in + * the ACPI DMAR table. This means that the platform boot firmware has made + * sure no device can issue DMA outside of RMRR regions. + */ +bool dmar_platform_optin(void) +{ + struct acpi_table_dmar *dmar; + acpi_status status; + bool ret; + + status = acpi_get_table(ACPI_SIG_DMAR, 0, + (struct acpi_table_header **)&dmar); + if (ACPI_FAILURE(status)) + return false; + + ret = !!(dmar->flags & DMAR_PLATFORM_OPT_IN); + acpi_put_table((struct acpi_table_header *)dmar); + + return ret; +} +EXPORT_SYMBOL_GPL(dmar_platform_optin); diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 41a4b8808802..30e8584137f5 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -184,6 +184,7 @@ static int rwbf_quirk; */ static int force_on = 0; int intel_iommu_tboot_noforce; +static int no_platform_optin; #define ROOT_ENTRY_NR (VTD_PAGE_SIZE/sizeof(struct root_entry)) @@ -503,6 +504,7 @@ static int __init intel_iommu_setup(char *str) pr_info("IOMMU enabled\n"); } else if (!strncmp(str, "off", 3)) { dmar_disabled = 1; + no_platform_optin = 1; pr_info("IOMMU disabled\n"); } else if (!strncmp(str, "igfx_off", 8)) { dmar_map_gfx = 0; @@ -2895,6 +2897,13 @@ static int iommu_should_identity_map(struct device *dev, int startup) if (device_is_rmrr_locked(dev)) return 0; + /* + * Prevent any device marked as untrusted from getting + * placed into the statically identity mapping domain. + */ + if (pdev->untrusted) + return 0; + if ((iommu_identity_mapping & IDENTMAP_AZALIA) && IS_AZALIA(pdev)) return 1; @@ -4728,14 +4737,54 @@ const struct attribute_group *intel_iommu_groups[] = { NULL, }; +static int __init platform_optin_force_iommu(void) +{ + struct pci_dev *pdev = NULL; + bool has_untrusted_dev = false; + + if (!dmar_platform_optin() || no_platform_optin) + return 0; + + for_each_pci_dev(pdev) { + if (pdev->untrusted) { + has_untrusted_dev = true; + break; + } + } + + if (!has_untrusted_dev) + return 0; + + if (no_iommu || dmar_disabled) + pr_info("Intel-IOMMU force enabled due to platform opt in\n"); + + /* + * If Intel-IOMMU is disabled by default, we will apply identity + * map for all devices except those marked as being untrusted. + */ + if (dmar_disabled) + iommu_identity_mapping |= IDENTMAP_ALL; + + dmar_disabled = 0; +#if defined(CONFIG_X86) && defined(CONFIG_SWIOTLB) + swiotlb = 0; +#endif + no_iommu = 0; + + return 1; +} + int __init intel_iommu_init(void) { int ret = -ENODEV; struct dmar_drhd_unit *drhd; struct intel_iommu *iommu; - /* VT-d is required for a TXT/tboot launch, so enforce that */ - force_on = tboot_force_iommu(); + /* + * Intel IOMMU is required for a TXT/tboot launch or platform + * opt in, so enforce that. + */ + force_on = tboot_force_iommu() || platform_optin_force_iommu(); if (iommu_init_mempool()) { if (force_on) diff --git a/include/linux/dmar.h b/include/linux/dmar.h index 843a41ba7e28..f8af1d770520 100644 --- a/include/linux/dmar.h +++ b/include/linux/dmar.h @@ -39,6 +39,7 @@ struct acpi_dmar_header; /* DMAR Flags */ #define DMAR_INTR_REMAP 0x1 #define DMAR_X2APIC_OPT_OUT 0x2 +#define DMAR_PLATFORM_OPT_IN 0x4 struct intel_iommu; @@ -170,6 +171,8 @@ static inline int dmar_ir_hotplug(struct dmar_drhd_unit *dmaru, bool insert) { return 0; } #endif /* CONFIG_IRQ_REMAP */ +extern bool dmar_platform_optin(void); + #else /* CONFIG_DMAR_TABLE */ static inline int dmar_device_add(void *handle) @@ -182,6 +185,11 @@ static inline int dmar_device_remove(void *handle) return 0; } +static inline bool dmar_platform_optin(void) +{ + return false; +} + #endif /* CONFIG_DMAR_TABLE */ struct irte { From patchwork Thu Nov 29 15:51:52 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mika Westerberg X-Patchwork-Id: 10704823 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0154317D5 for ; Thu, 29 Nov 2018 15:52:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E5CE42F4AE for ; Thu, 29 Nov 2018 15:52:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D99C52F4C9; Thu, 29 Nov 2018 15:52:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 48FA72F4AE for ; Thu, 29 Nov 2018 15:52:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729169AbeK3C5t (ORCPT ); Thu, 29 Nov 2018 21:57:49 -0500 Received: from mga17.intel.com ([192.55.52.151]:36149 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728986AbeK3C5s (ORCPT ); Thu, 29 Nov 2018 21:57:48 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Nov 2018 07:52:00 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,295,1539673200"; d="scan'208";a="113572807" Received: from black.fi.intel.com ([10.237.72.28]) by orsmga002.jf.intel.com with ESMTP; 29 Nov 2018 07:51:54 -0800 Received: by black.fi.intel.com (Postfix, from userid 1001) id E7ACB2A9; Thu, 29 Nov 2018 17:51:53 +0200 (EET) From: Mika Westerberg To: iommu@lists.linux-foundation.org Cc: Joerg Roedel , David Woodhouse , Lu Baolu , Ashok Raj , Bjorn Helgaas , "Rafael J. Wysocki" , Jacob jun Pan , Andreas Noever , Michael Jamet , Yehezkel Bernat , Lukas Wunner , Christian Kellner , Mario.Limonciello@dell.com, Anthony Wong , Lorenzo Pieralisi , Christoph Hellwig , Alex Williamson , Mika Westerberg , linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 3/4] iommu/vt-d: Do not enable ATS for untrusted devices Date: Thu, 29 Nov 2018 18:51:52 +0300 Message-Id: <20181129155153.35840-4-mika.westerberg@linux.intel.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181129155153.35840-1-mika.westerberg@linux.intel.com> References: <20181129155153.35840-1-mika.westerberg@linux.intel.com> MIME-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently Linux automatically enables ATS (Address Translation Service) for any device that supports it (and IOMMU is turned on). ATS is used to accelerate DMA access as the device can cache translations locally so there is no need to do full translation on IOMMU side. However, as pointed out in [1] ATS can be used to bypass IOMMU based security completely by simply sending PCIe read/write transaction with AT (Address Translation) field set to "translated". To mitigate this modify the Intel IOMMU code so that it does not enable ATS for any device that is marked as being untrusted. In case this turns out to cause performance issues we may selectively allow ATS based on user decision but currently use big hammer and disable it completely to be on the safe side. [1] https://www.repository.cam.ac.uk/handle/1810/274352 Signed-off-by: Mika Westerberg Reviewed-by: Ashok Raj Reviewed-by: Joerg Roedel Acked-by: Joerg Roedel --- drivers/iommu/intel-iommu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 30e8584137f5..adc2c9619e56 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -1473,7 +1473,8 @@ static void iommu_enable_dev_iotlb(struct device_domain_info *info) if (info->pri_supported && !pci_reset_pri(pdev) && !pci_enable_pri(pdev, 32)) info->pri_enabled = 1; #endif - if (info->ats_supported && !pci_enable_ats(pdev, VTD_PAGE_SHIFT)) { + if (!pdev->untrusted && info->ats_supported && + !pci_enable_ats(pdev, VTD_PAGE_SHIFT)) { info->ats_enabled = 1; domain_update_iotlb(info->domain); info->ats_qdep = pci_ats_queue_depth(pdev); From patchwork Thu Nov 29 15:51:53 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mika Westerberg X-Patchwork-Id: 10704807 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D1F6F13AD for ; Thu, 29 Nov 2018 15:52:03 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C22FE2F404 for ; Thu, 29 Nov 2018 15:52:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B5F732F47D; Thu, 29 Nov 2018 15:52:03 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A38442F404 for ; Thu, 29 Nov 2018 15:52:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729147AbeK3C5t (ORCPT ); Thu, 29 Nov 2018 21:57:49 -0500 Received: from mga04.intel.com ([192.55.52.120]:65045 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729044AbeK3C5t (ORCPT ); Thu, 29 Nov 2018 21:57:49 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Nov 2018 07:52:00 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,295,1539673200"; d="scan'208";a="113754391" Received: from black.fi.intel.com ([10.237.72.28]) by orsmga001.jf.intel.com with ESMTP; 29 Nov 2018 07:51:54 -0800 Received: by black.fi.intel.com (Postfix, from userid 1001) id 05843325; Thu, 29 Nov 2018 17:51:53 +0200 (EET) From: Mika Westerberg To: iommu@lists.linux-foundation.org Cc: Joerg Roedel , David Woodhouse , Lu Baolu , Ashok Raj , Bjorn Helgaas , "Rafael J. Wysocki" , Jacob jun Pan , Andreas Noever , Michael Jamet , Yehezkel Bernat , Lukas Wunner , Christian Kellner , Mario.Limonciello@dell.com, Anthony Wong , Lorenzo Pieralisi , Christoph Hellwig , Alex Williamson , Mika Westerberg , linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 4/4] thunderbolt: Export IOMMU based DMA protection support to userspace Date: Thu, 29 Nov 2018 18:51:53 +0300 Message-Id: <20181129155153.35840-5-mika.westerberg@linux.intel.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181129155153.35840-1-mika.westerberg@linux.intel.com> References: <20181129155153.35840-1-mika.westerberg@linux.intel.com> MIME-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Recent systems with Thunderbolt ports may support IOMMU natively. In practice this means that Thunderbolt connected devices are placed behind an IOMMU during the whole time it is connected (including during boot) making Thunderbolt security levels redundant. This is called Kernel DMA protection [1] by Microsoft. Some of these systems still have Thunderbolt security level set to "user" in order to support OS downgrade (the older version of the OS might not support IOMMU based DMA protection so connecting a device still relies on user approval). Export this information to userspace by introducing a new sysfs attribute (iommu_dma_protection). Based on it userspace tools can make more accurate decision whether or not authorize the connected device. In addition update Thunderbolt documentation regarding IOMMU based DMA protection. [1] https://docs.microsoft.com/en-us/windows/security/information-protection/kernel-dma-protection-for-thunderbolt Signed-off-by: Mika Westerberg Reviewed-by: Yehezkel Bernat --- .../ABI/testing/sysfs-bus-thunderbolt | 9 +++++++++ Documentation/admin-guide/thunderbolt.rst | 20 +++++++++++++++++++ drivers/thunderbolt/domain.c | 17 ++++++++++++++++ 3 files changed, 46 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-thunderbolt b/Documentation/ABI/testing/sysfs-bus-thunderbolt index 151584a1f950..b21fba14689b 100644 --- a/Documentation/ABI/testing/sysfs-bus-thunderbolt +++ b/Documentation/ABI/testing/sysfs-bus-thunderbolt @@ -21,6 +21,15 @@ Description: Holds a comma separated list of device unique_ids that If a device is authorized automatically during boot its boot attribute is set to 1. +What: /sys/bus/thunderbolt/devices/.../domainX/iommu_dma_protection +Date: Mar 2019 +KernelVersion: 4.21 +Contact: thunderbolt-software@lists.01.org +Description: This attribute tells whether the system uses IOMMU + for DMA protection. Value of 1 means IOMMU is used 0 means + it is not (DMA protection is solely based on Thunderbolt + security levels). + What: /sys/bus/thunderbolt/devices/.../domainX/security Date: Sep 2017 KernelVersion: 4.13 diff --git a/Documentation/admin-guide/thunderbolt.rst b/Documentation/admin-guide/thunderbolt.rst index 35fccba6a9a6..898ad78f3cc7 100644 --- a/Documentation/admin-guide/thunderbolt.rst +++ b/Documentation/admin-guide/thunderbolt.rst @@ -133,6 +133,26 @@ If the user still wants to connect the device they can either approve the device without a key or write a new key and write 1 to the ``authorized`` file to get the new key stored on the device NVM. +DMA protection utilizing IOMMU +------------------------------ +Recent systems from 2018 and forward with Thunderbolt ports may natively +support IOMMU. This means that Thunderbolt security is handled by an IOMMU +so connected devices cannot access memory regions outside of what is +allocated for them by drivers. When Linux is running on such system it +automatically enables IOMMU if not enabled by the user already. These +systems can be identified by reading ``1`` from +``/sys/bus/thunderbolt/devices/domainX/iommu_dma_protection`` attribute. + +The driver does not do anything special in this case but because DMA +protection is handled by the IOMMU, security levels (if set) are +redundant. For this reason some systems ship with security level set to +``none``. Other systems have security level set to ``user`` in order to +support downgrade to older OS, so users who want to automatically +authorize devices when IOMMU DMA protection is enabled can use the +following ``udev`` rule:: + + ACTION=="add", SUBSYSTEM=="thunderbolt", ATTRS{iommu_dma_protection}=="1", ATTR{authorized}=="0", ATTR{authorized}="1" + Upgrading NVM on Thunderbolt device or host ------------------------------------------- Since most of the functionality is handled in firmware running on a diff --git a/drivers/thunderbolt/domain.c b/drivers/thunderbolt/domain.c index 93e562f18d40..7416bdbd8576 100644 --- a/drivers/thunderbolt/domain.c +++ b/drivers/thunderbolt/domain.c @@ -7,7 +7,9 @@ */ #include +#include #include +#include #include #include #include @@ -236,6 +238,20 @@ static ssize_t boot_acl_store(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR_RW(boot_acl); +static ssize_t iommu_dma_protection_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + /* + * Kernel DMA protection is a feature where Thunderbolt security is + * handled natively using IOMMU. It is enabled when IOMMU is + * enabled and ACPI DMAR table has DMAR_PLATFORM_OPT_IN set. + */ + return sprintf(buf, "%d\n", + iommu_present(&pci_bus_type) && dmar_platform_optin()); +} +static DEVICE_ATTR_RO(iommu_dma_protection); + static ssize_t security_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -251,6 +267,7 @@ static DEVICE_ATTR_RO(security); static struct attribute *domain_attrs[] = { &dev_attr_boot_acl.attr, + &dev_attr_iommu_dma_protection.attr, &dev_attr_security.attr, NULL, };