From patchwork Wed Apr 7 20:49:35 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Huang, Kai" X-Patchwork-Id: 12189385 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 7664BC43460 for ; Wed, 7 Apr 2021 20:50:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 574D26120E for ; Wed, 7 Apr 2021 20:50:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231535AbhDGUur (ORCPT ); Wed, 7 Apr 2021 16:50:47 -0400 Received: from mga05.intel.com ([192.55.52.43]:47246 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231508AbhDGUun (ORCPT ); Wed, 7 Apr 2021 16:50:43 -0400 IronPort-SDR: VCIlbXH3ibqG3q2yB4O1j3ZzlbN6mmITIj+b+A5UAvWy1liNCsbgfilHCVk8EMOr7KhIBAhd/z RJlkCiUq1ivA== X-IronPort-AV: E=McAfee;i="6000,8403,9947"; a="278660421" X-IronPort-AV: E=Sophos;i="5.82,204,1613462400"; d="scan'208";a="278660421" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Apr 2021 13:50:33 -0700 IronPort-SDR: 7C2TD1WJHGa4ABbt3uxljRe8/MJRmva1RTbDpwgFTBKf4QhlbOpI05Lo9ql2aI02Ow4P1ckqp/ tsj1sRTJQ8ig== X-IronPort-AV: E=Sophos;i="5.82,204,1613462400"; d="scan'208";a="415437507" Received: from tkokeray-mobl.amr.corp.intel.com (HELO khuang2-desk.gar.corp.intel.com) ([10.254.113.100]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Apr 2021 13:50:30 -0700 From: Kai Huang To: kvm@vger.kernel.org, linux-sgx@vger.kernel.org Cc: seanjc@google.com, pbonzini@redhat.com, bp@alien8.de, jarkko@kernel.org, dave.hansen@intel.com, luto@kernel.org, rick.p.edgecombe@intel.com, haitao.huang@intel.com, Andy Lutomirski , Kai Huang Subject: [PATCH v4 11/11] KVM: x86: Add capability to grant VM access to privileged SGX attribute Date: Thu, 8 Apr 2021 08:49:35 +1200 Message-Id: <78179bb5dfde6cff7b1e4df8ead5b3674018079b.1617825858.git.kai.huang@intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org From: Sean Christopherson Add a capability, KVM_CAP_SGX_ATTRIBUTE, that can be used by userspace to grant a VM access to a priveleged attribute, with args[0] holding a file handle to a valid SGX attribute file. The SGX subsystem restricts access to a subset of enclave attributes to provide additional security for an uncompromised kernel, e.g. to prevent malware from using the PROVISIONKEY to ensure its nodes are running inside a geniune SGX enclave and/or to obtain a stable fingerprint. To prevent userspace from circumventing such restrictions by running an enclave in a VM, KVM restricts guest access to privileged attributes by default. Cc: Andy Lutomirski Signed-off-by: Sean Christopherson Signed-off-by: Kai Huang --- Documentation/virt/kvm/api.rst | 23 +++++++++++++++++++++++ arch/x86/kvm/cpuid.c | 2 +- arch/x86/kvm/x86.c | 21 +++++++++++++++++++++ include/uapi/linux/kvm.h | 1 + 4 files changed, 46 insertions(+), 1 deletion(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 38e327d4b479..ebb47e48d4f3 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6230,6 +6230,29 @@ KVM_RUN_BUS_LOCK flag is used to distinguish between them. This capability can be used to check / enable 2nd DAWR feature provided by POWER10 processor. +7.24 KVM_CAP_SGX_ATTRIBUTE +---------------------- + +:Architectures: x86 +:Target: VM +:Parameters: args[0] is a file handle of a SGX attribute file in securityfs +:Returns: 0 on success, -EINVAL if the file handle is invalid or if a requested + attribute is not supported by KVM. + +KVM_CAP_SGX_ATTRIBUTE enables a userspace VMM to grant a VM access to one or +more priveleged enclave attributes. args[0] must hold a file handle to a valid +SGX attribute file corresponding to an attribute that is supported/restricted +by KVM (currently only PROVISIONKEY). + +The SGX subsystem restricts access to a subset of enclave attributes to provide +additional security for an uncompromised kernel, e.g. use of the PROVISIONKEY +is restricted to deter malware from using the PROVISIONKEY to obtain a stable +system fingerprint. To prevent userspace from circumventing such restrictions +by running an enclave in a VM, KVM prevents access to privileged attributes by +default. + +See Documentation/x86/sgx/2.Kernel-internals.rst for more details. + 8. Other capabilities. ====================== diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index a0d45607b702..6dc12d949f86 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -849,7 +849,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) * expected to derive it from supported XCR0. */ entry->eax &= SGX_ATTR_DEBUG | SGX_ATTR_MODE64BIT | - /* PROVISIONKEY | */ SGX_ATTR_EINITTOKENKEY | + SGX_ATTR_PROVISIONKEY | SGX_ATTR_EINITTOKENKEY | SGX_ATTR_KSS; entry->ebx &= 0; break; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d2da5abcf395..81139e076380 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -75,6 +75,7 @@ #include #include #include +#include #include #define CREATE_TRACE_POINTS @@ -3759,6 +3760,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_X86_USER_SPACE_MSR: case KVM_CAP_X86_MSR_FILTER: case KVM_CAP_ENFORCE_PV_FEATURE_CPUID: +#ifdef CONFIG_X86_SGX_KVM + case KVM_CAP_SGX_ATTRIBUTE: +#endif r = 1; break; #ifdef CONFIG_KVM_XEN @@ -5345,6 +5349,23 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, kvm->arch.bus_lock_detection_enabled = true; r = 0; break; +#ifdef CONFIG_X86_SGX_KVM + case KVM_CAP_SGX_ATTRIBUTE: { + unsigned long allowed_attributes = 0; + + r = sgx_set_attribute(&allowed_attributes, cap->args[0]); + if (r) + break; + + /* KVM only supports the PROVISIONKEY privileged attribute. */ + if ((allowed_attributes & SGX_ATTR_PROVISIONKEY) && + !(allowed_attributes & ~SGX_ATTR_PROVISIONKEY)) + kvm->arch.sgx_provisioning_allowed = true; + else + r = -EINVAL; + break; + } +#endif default: r = -EINVAL; break; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index f6afee209620..7d8927e474f8 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1078,6 +1078,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_DIRTY_LOG_RING 192 #define KVM_CAP_X86_BUS_LOCK_EXIT 193 #define KVM_CAP_PPC_DAWR1 194 +#define KVM_CAP_SGX_ATTRIBUTE 195 #ifdef KVM_CAP_IRQ_ROUTING