From: Kai Huang <kai.huang@intel.com>
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 <luto@amacapital.net>,
Kai Huang <kai.huang@intel.com>
Subject: [RFC PATCH v4 26/26] KVM: x86: Add capability to grant VM access to privileged SGX attribute
Date: Mon, 8 Feb 2021 23:56:33 +1300 [thread overview]
Message-ID: <897b4a9088dc04a674b8bf244d465ebac042a8a2.1612777752.git.kai.huang@intel.com> (raw)
In-Reply-To: <cover.1612777752.git.kai.huang@intel.com>
From: Sean Christopherson <sean.j.christopherson@intel.com>
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 <luto@amacapital.net>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
---
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 <asm/tlbflush.h>
#include <asm/intel_pt.h>
#include <asm/emulate_prefix.h>
+#include <asm/sgx.h>
+#include <asm/sgx_arch.h>
#include <clocksource/hyperv_timer.h>
#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
--
2.29.2
prev parent reply other threads:[~2021-02-08 11:00 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-08 10:53 [RFC PATCH v4 00/26] KVM SGX virtualization support Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 01/26] x86/cpufeatures: Make SGX_LC feature bit depend on SGX bit Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 02/26] x86/cpufeatures: Add SGX1 and SGX2 sub-features Kai Huang
2021-02-09 16:11 ` Dave Hansen
2021-02-08 10:54 ` [RFC PATCH v4 03/26] x86/sgx: Wipe out EREMOVE from sgx_free_epc_page() Kai Huang
2021-02-09 16:18 ` Dave Hansen
2021-02-09 18:26 ` Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 04/26] x86/sgx: Add SGX_CHILD_PRESENT hardware error code Kai Huang
2021-02-09 16:24 ` Dave Hansen
2021-02-09 16:48 ` Sean Christopherson
2021-02-09 16:52 ` Dave Hansen
2021-02-09 17:07 ` Sean Christopherson
2021-02-09 21:03 ` Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 05/26] x86/sgx: Introduce virtual EPC for use by KVM guests Kai Huang
2021-02-09 21:18 ` Jarkko Sakkinen
2021-02-09 21:19 ` Jarkko Sakkinen
2021-02-09 21:36 ` Dave Hansen
2021-02-10 0:20 ` Kai Huang
2021-02-10 16:52 ` Sean Christopherson
2021-02-10 23:12 ` Kai Huang
2021-02-12 12:17 ` [RFC PATCH v4 05/26] x86/sgx: Introduce virtual EPC for use by KVM guests' Jarkko Sakkinen
2021-02-13 13:33 ` Kai Huang
2021-02-12 12:15 ` [RFC PATCH v4 05/26] x86/sgx: Introduce virtual EPC for use by KVM guests Jarkko Sakkinen
2021-02-12 12:14 ` Jarkko Sakkinen
2021-02-08 10:54 ` [RFC PATCH v4 06/26] x86/cpu/intel: Allow SGX virtualization without Launch Control support Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 07/26] x86/sgx: Initialize virtual EPC driver even when SGX driver is disabled Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 08/26] x86/sgx: Expose SGX architectural definitions to the kernel Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 09/26] x86/sgx: Move ENCLS leaf definitions to sgx_arch.h Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 10/26] x86/sgx: Add SGX2 ENCLS leaf definitions (EAUG, EMODPR and EMODT) Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 11/26] x86/sgx: Add encls_faulted() helper Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 12/26] x86/sgx: Add helper to update SGX_LEPUBKEYHASHn MSRs Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 13/26] x86/sgx: Add helpers to expose ECREATE and EINIT to KVM Kai Huang
2021-02-08 10:54 ` [RFC PATCH v4 14/26] x86/sgx: Move provisioning device creation out of SGX driver Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 15/26] KVM: VMX: Convert vcpu_vmx.exit_reason to a union Kai Huang
2021-02-08 11:11 ` Kai Huang
2021-02-08 14:39 ` Xiaoyao Li
2021-02-09 0:09 ` Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 16/26] KVM: x86: Export kvm_mmu_gva_to_gpa_{read,write}() for SGX (VMX) Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 17/26] KVM: x86: Define new #PF SGX error code bit Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 18/26] KVM: x86: Add support for reverse CPUID lookup of scattered features Kai Huang
2021-02-08 11:05 ` Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 19/26] KVM: x86: Add reverse-CPUID lookup support for scattered SGX features Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 20/26] KVM: VMX: Add basic handling of VM-Exit from SGX enclave Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 21/26] KVM: VMX: Frame in ENCLS handler for SGX virtualization Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 22/26] KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 23/26] KVM: VMX: Add emulation of SGX Launch Control LE hash MSRs Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 24/26] KVM: VMX: Add ENCLS[EINIT] handler to support SGX Launch Control (LC) Kai Huang
2021-02-08 10:55 ` [RFC PATCH v4 25/26] KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC Kai Huang
2021-02-08 10:56 ` Kai Huang [this message]
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