linux-kernel - [RFC KVM 02/27] KVM: x86: Introduce address_space

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 13 May 2019 16:38:10 +0200
From:   Alexandre Chartre <alexandre.chartre@...cle.com>
To:     pbonzini@...hat.com, rkrcmar@...hat.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        kvm@...r.kernel.org, x86@...nel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     konrad.wilk@...cle.com, jan.setjeeilers@...cle.com,
        liran.alon@...cle.com, jwadams@...gle.com,
        alexandre.chartre@...cle.com
Subject: [RFC KVM 02/27] KVM: x86: Introduce address_space_isolation module parameter

From: Liran Alon <liran.alon@...cle.com>

Add the address_space_isolation parameter to the kvm module.

When set to true, KVM #VMExit handlers run in isolated address space
which maps only KVM required code and per-VM information instead of
entire kernel address space.

This mechanism is meant to mitigate memory-leak side-channels CPU
vulnerabilities (e.g. Spectre, L1TF and etc.) but can also be viewed
as security in-depth as it also helps generically against info-leaks
vulnerabilities in KVM #VMExit handlers and reduce the available
gadgets for ROP attacks.

This is set to false by default because it incurs a performance hit
which some users will not want to take for security gain.

Signed-off-by: Liran Alon <liran.alon@...cle.com>
Signed-off-by: Alexandre Chartre <alexandre.chartre@...cle.com>
---
 arch/x86/kvm/Makefile    |    2 +-
 arch/x86/kvm/isolation.c |   26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletions(-)
 create mode 100644 arch/x86/kvm/isolation.c

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index 31ecf7a..9f404e9 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -10,7 +10,7 @@ kvm-$(CONFIG_KVM_ASYNC_PF)	+= $(KVM)/async_pf.o
 
 kvm-y			+= x86.o mmu.o emulate.o i8259.o irq.o lapic.o \
 			   i8254.o ioapic.o irq_comm.o cpuid.o pmu.o mtrr.o \
-			   hyperv.o page_track.o debugfs.o
+			   hyperv.o page_track.o debugfs.o isolation.o
 
 kvm-intel-y		+= vmx/vmx.o vmx/vmenter.o vmx/pmu_intel.o vmx/vmcs12.o vmx/evmcs.o vmx/nested.o
 kvm-amd-y		+= svm.o pmu_amd.o
diff --git a/arch/x86/kvm/isolation.c b/arch/x86/kvm/isolation.c
new file mode 100644
index 0000000..e25f663
--- /dev/null
+++ b/arch/x86/kvm/isolation.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ *
+ * KVM Address Space Isolation
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+
+/*
+ * When set to true, KVM #VMExit handlers run in isolated address space
+ * which maps only KVM required code and per-VM information instead of
+ * entire kernel address space.
+ *
+ * This mechanism is meant to mitigate memory-leak side-channels CPU
+ * vulnerabilities (e.g. Spectre, L1TF and etc.) but can also be viewed
+ * as security in-depth as it also helps generically against info-leaks
+ * vulnerabilities in KVM #VMExit handlers and reduce the available
+ * gadgets for ROP attacks.
+ *
+ * This is set to false by default because it incurs a performance hit
+ * which some users will not want to take for security gain.
+ */
+static bool __read_mostly address_space_isolation;
+module_param(address_space_isolation, bool, 0444);
-- 
1.7.1