From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756135AbZJAXm4 (ORCPT ); Thu, 1 Oct 2009 19:42:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753894AbZJAXmy (ORCPT ); Thu, 1 Oct 2009 19:42:54 -0400 Received: from kroah.org ([198.145.64.141]:42032 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755258AbZJAXiI (ORCPT ); Thu, 1 Oct 2009 19:38:08 -0400 X-Mailbox-Line: From gregkh@mini.kroah.org Thu Oct 1 16:33:20 2009 Message-Id: <20091001233320.245354779@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Thu, 01 Oct 2009 16:31:26 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jan Kiszka , avi@redhat.com Subject: [patch 10/30] KVM: x86: Disallow hypercalls for guest callers in rings > 0 References: <20091001233116.947658905@mini.kroah.org> Content-Disposition: inline; filename=kvm-x86-disallow-hypercalls-for-guest-callers-in-rings-0.patch In-Reply-To: <20091001233504.GA17709@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.30-stable review patch. If anyone has any objections, please let us know. ------------------ From: Jan Kiszka (cherry picked from commit 07708c4af1346ab1521b26a202f438366b7bcffd) So far unprivileged guest callers running in ring 3 can issue, e.g., MMU hypercalls. Normally, such callers cannot provide any hand-crafted MMU command structure as it has to be passed by its physical address, but they can still crash the guest kernel by passing random addresses. To close the hole, this patch considers hypercalls valid only if issued from guest ring 0. This may still be relaxed on a per-hypercall base in the future once required. Signed-off-by: Jan Kiszka Signed-off-by: Avi Kivity Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/x86.c | 6 ++++++ include/linux/kvm_para.h | 1 + 2 files changed, 7 insertions(+) --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2898,6 +2898,11 @@ int kvm_emulate_hypercall(struct kvm_vcp a3 &= 0xFFFFFFFF; } + if (kvm_x86_ops->get_cpl(vcpu) != 0) { + ret = -KVM_EPERM; + goto out; + } + switch (nr) { case KVM_HC_VAPIC_POLL_IRQ: ret = 0; @@ -2909,6 +2914,7 @@ int kvm_emulate_hypercall(struct kvm_vcp ret = -KVM_ENOSYS; break; } +out: kvm_register_write(vcpu, VCPU_REGS_RAX, ret); ++vcpu->stat.hypercalls; return r; --- a/include/linux/kvm_para.h +++ b/include/linux/kvm_para.h @@ -13,6 +13,7 @@ #define KVM_ENOSYS 1000 #define KVM_EFAULT EFAULT #define KVM_E2BIG E2BIG +#define KVM_EPERM EPERM #define KVM_HC_VAPIC_POLL_IRQ 1 #define KVM_HC_MMU_OP 2