From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757173AbZHZKaR (ORCPT ); Wed, 26 Aug 2009 06:30:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757143AbZHZKaP (ORCPT ); Wed, 26 Aug 2009 06:30:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:9008 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756747AbZHZKaK (ORCPT ); Wed, 26 Aug 2009 06:30:10 -0400 From: Avi Kivity To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH 04/47] KVM: x86: Disallow hypercalls for guest callers in rings > 0 Date: Wed, 26 Aug 2009 13:29:26 +0300 Message-Id: <1251282609-12835-5-git-send-email-avi@redhat.com> In-Reply-To: <1251282609-12835-1-git-send-email-avi@redhat.com> References: <1251282609-12835-1-git-send-email-avi@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jan Kiszka 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. Cc: stable@kernel.org Signed-off-by: Jan Kiszka Signed-off-by: Avi Kivity --- arch/x86/kvm/x86.c | 6 ++++++ include/linux/kvm_para.h | 1 + 2 files changed, 7 insertions(+), 0 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index fa525d5..92b5edd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3213,6 +3213,11 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) 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; @@ -3224,6 +3229,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) ret = -KVM_ENOSYS; break; } +out: kvm_register_write(vcpu, VCPU_REGS_RAX, ret); ++vcpu->stat.hypercalls; return r; diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h index 3ddce03..d731092 100644 --- 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 -- 1.6.4.1