From patchwork Wed Nov 3 11:52:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emanuele Giuseppe Esposito X-Patchwork-Id: 12600645 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2C7BC433F5 for ; Wed, 3 Nov 2021 11:53:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8641061101 for ; Wed, 3 Nov 2021 11:53:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231910AbhKCL4L (ORCPT ); Wed, 3 Nov 2021 07:56:11 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:51329 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231869AbhKCL4I (ORCPT ); Wed, 3 Nov 2021 07:56:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1635940412; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=L/P3UrVYThs6BCBvUjnusHuZyMwrK4mhs8KvOceIMpY=; b=NSSXeDo7dqBE8YlnNy9ygtJmBYUoTQnnOi9uz/p3147z9ldIou64eRvuT22Woz+R8rQgSH dKFrxSCYE8nUPu7IiwT6+8+oToKStwQn5Y9TFnKVrNXdI5VkQKxBB0wfJoQAWyLO/eUYBd SxlQDkSAxZ2eQLFC1VK3ye9Zn9I6DZI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-500-duE2122INUOu_nTgl2chhw-1; Wed, 03 Nov 2021 07:53:29 -0400 X-MC-Unique: duE2122INUOu_nTgl2chhw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 00D1F8066EF; Wed, 3 Nov 2021 11:53:26 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4148A19741; Wed, 3 Nov 2021 11:53:15 +0000 (UTC) From: Emanuele Giuseppe Esposito To: kvm@vger.kernel.org Cc: Paolo Bonzini , Maxim Levitsky , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, Emanuele Giuseppe Esposito Subject: [PATCH v4 0/7] KVM: nSVM: avoid TOC/TOU race when checking vmcb12 Date: Wed, 3 Nov 2021 07:52:23 -0400 Message-Id: <20211103115230.720154-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Currently there is a TOC/TOU race between the check of vmcb12's efer, cr0 and cr4 registers and the later save of their values in svm_set_*, because the guest could modify the values in the meanwhile. To solve this issue, this series introduces and uses svm->nested.save structure in enter_svm_guest_mode to save the current value of efer, cr0 and cr4 and later use these to set the vcpu->arch.* state. Similarly, svm->nested.ctl contains fields that are not used, so having a full vmcb_control_area means passing uninitialized fields. Patches 1,3 and 8 take care of renaming and refactoring code. Patches 2 and 6 introduce respectively vmcb_ctrl_area_cached and vmcb_save_area_cached. Patches 4 and 5 use vmcb_save_area_cached to avoid TOC/TOU, and patch 7 uses vmcb_ctrl_area_cached. Signed-off-by: Emanuele Giuseppe Esposito --- v4: * introduce _* helpers (_nested_vmcb_check_save, _nested_copy_vmcb_control_to_cache, _nested_copy_vmcb_save_to_cache) that take care of additional parameters. * svm_set_nested_state: introduce {save, ctl}_cached variables to not pollute svm->nested.{save,ctl} state, especially if the check fails. remove also unnecessary memset added in previous versions. * svm_get_nested_state: change stack variable ctl introduced in this series into a pointer that will be zeroed and freed after it has been copied to user v3: * merge this series with "KVM: nSVM: use vmcb_ctrl_area_cached instead of vmcb_control_area in nested state" * rename "nested_load_save_from_vmcb12" in "nested_copy_vmcb_save_to_cache" * rename "nested_load_control_from_vmcb12" in "nested_copy_vmcb_control_to_cache" * change check functions (nested_vmcb_valid_sregs and nested_vmcb_valid_sregs) to accept only the vcpu parameter, since we only check nested state now * rename "vmcb_is_intercept_cached" in "vmcb12_is_intercept" and duplicate the implementation instead of calling vmcb_is_intercept v2: * svm->nested.save is a separate struct vmcb_save_area_cached, and not vmcb_save_area. * update also vmcb02->cr3 with svm->nested.save.cr3 RFC: * use svm->nested.save instead of local variables. * not dependent anymore from "KVM: nSVM: remove useless kvm_clear_*_queue" * simplified patches, we just use the struct and not move the check nearer to the TOU. Emanuele Giuseppe Esposito (7): KVM: nSVM: move nested_vmcb_check_cr3_cr4 logic in nested_vmcb_valid_sregs nSVM: introduce smv->nested.save to cache save area fields nSVM: rename nested_load_control_from_vmcb12 in nested_copy_vmcb_control_to_cache nSVM: use vmcb_save_area_cached in nested_vmcb_valid_sregs() nSVM: use svm->nested.save to load vmcb12 registers and avoid TOC/TOU races nSVM: introduce struct vmcb_ctrl_area_cached nSVM: use vmcb_ctrl_area_cached instead of vmcb_control_area in struct svm_nested_state arch/x86/kvm/svm/nested.c | 250 ++++++++++++++++++++++++-------------- arch/x86/kvm/svm/svm.c | 7 +- arch/x86/kvm/svm/svm.h | 57 ++++++++- 3 files changed, 212 insertions(+), 102 deletions(-)