From patchwork Sat Feb 13 13:30:45 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Huang, Kai" X-Patchwork-Id: 12086839 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,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 A14C8C433DB for ; Sat, 13 Feb 2021 13:33:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 76AE064E50 for ; Sat, 13 Feb 2021 13:33:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229771AbhBMNdf (ORCPT ); Sat, 13 Feb 2021 08:33:35 -0500 Received: from mga05.intel.com ([192.55.52.43]:55920 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229861AbhBMNcy (ORCPT ); Sat, 13 Feb 2021 08:32:54 -0500 IronPort-SDR: bH/UfTBdE0OK3d4L47N7gBBFYMI/CAl98+zgv8zecLFvY3AcZefAjv6EgRQz6mzLQ7dYgVwU9U gk/MglycZPdg== X-IronPort-AV: E=McAfee;i="6000,8403,9893"; a="267371909" X-IronPort-AV: E=Sophos;i="5.81,176,1610438400"; d="scan'208";a="267371909" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Feb 2021 05:30:57 -0800 IronPort-SDR: od26tjulHm6ZJ8i0gMWcEmUMe0K3NnRwlus4FeK4hDJOpy3tOFgZaASjXbPJto1GDuVBfpLCRR lNwe/hjvPg0g== X-IronPort-AV: E=Sophos;i="5.81,176,1610438400"; d="scan'208";a="398366310" Received: from kshah-mobl1.amr.corp.intel.com (HELO khuang2-desk.gar.corp.intel.com) ([10.255.230.239]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Feb 2021 05:30:53 -0800 From: Kai Huang To: linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org Cc: seanjc@google.com, jarkko@kernel.org, luto@kernel.org, dave.hansen@intel.com, rick.p.edgecombe@intel.com, haitao.huang@intel.com, pbonzini@redhat.com, bp@alien8.de, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, jmattson@google.com, joro@8bytes.org, vkuznets@redhat.com, wanpengli@tencent.com, corbet@lwn.net, Andy Lutomirski , Kai Huang Subject: [RFC PATCH v5 26/26] KVM: x86: Add capability to grant VM access to privileged SGX attribute Date: Sun, 14 Feb 2021 02:30:45 +1300 Message-Id: <5cb830912bb6a641a3947a10743ff40d71b4e953.1613221549.git.kai.huang@intel.com> X-Mailer: git-send-email 2.29.2 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 | 22 ++++++++++++++++++++++ include/uapi/linux/kvm.h | 1 + 4 files changed, 47 insertions(+), 1 deletion(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index c136e254b496..47c7c7c33025 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6037,6 +6037,29 @@ KVM_EXIT_X86_RDMSR and KVM_EXIT_X86_WRMSR exit notifications which user space can then handle to implement model specific MSR handling and/or user notifications to inform a user that an MSR was not handled. +7.22 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 04b2f5de2d7b..ad00a1af1545 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -833,7 +833,7 @@ 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 5ca7b181a3ae..3d1b4113a57b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -74,6 +74,8 @@ #include #include #include +#include +#include #include #define CREATE_TRACE_POINTS @@ -3767,6 +3769,9 @@ 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; case KVM_CAP_SYNC_REGS: @@ -5295,6 +5300,23 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, kvm->arch.user_space_msr_mask = cap->args[0]; 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 374c67875cdb..e17bda18a9b4 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1058,6 +1058,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_ENFORCE_PV_FEATURE_CPUID 190 #define KVM_CAP_SYS_HYPERV_CPUID 191 #define KVM_CAP_DIRTY_LOG_RING 192 +#define KVM_CAP_SGX_ATTRIBUTE 200 #ifdef KVM_CAP_IRQ_ROUTING