From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 312A2C432C3 for ; Wed, 13 Nov 2019 18:44:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5C118206F0 for ; Wed, 13 Nov 2019 18:44:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727538AbfKMSoI (ORCPT ); Wed, 13 Nov 2019 13:44:08 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:38400 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727329AbfKMSoI (ORCPT ); Wed, 13 Nov 2019 13:44:08 -0500 Received: from pps.filterd (m0187473.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id xADIVr7j177256 for ; Wed, 13 Nov 2019 13:44:06 -0500 Received: from e06smtp04.uk.ibm.com (e06smtp04.uk.ibm.com [195.75.94.100]) by mx0a-001b2d01.pphosted.com with ESMTP id 2w7qdbnw7m-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 13 Nov 2019 13:44:06 -0500 Received: from localhost by e06smtp04.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 13 Nov 2019 18:43:58 -0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id xADIhvlN27000904 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 13 Nov 2019 18:43:57 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4354BAE055; Wed, 13 Nov 2019 18:43:57 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3A694AE051; Wed, 13 Nov 2019 18:43:56 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.145.34.102]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 13 Nov 2019 18:43:56 +0000 (GMT) Subject: Re: [PATCH] KVM: Forbid /dev/kvm being opened by a compat task when CONFIG_KVM_COMPAT=n To: Marc Zyngier , kvm@vger.kernel.org Cc: Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , James Morse , Julien Thierry , Suzuki K Poulose , James Hogan , Paul Mackerras , Janosch Frank , David Hildenbrand , Cornelia Huck , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Peter Maydell References: <20191113160523.16130-1-maz@kernel.org> From: Christian Borntraeger Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <20191113160523.16130-1-maz@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19111318-0016-0000-0000-000002C3619B X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19111318-0017-0000-0000-00003324FF3D Message-Id: <2b846839-ea81-e40c-5106-90776d964e33@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-11-13_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1910280000 definitions=main-1911130158 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 13.11.19 17:05, Marc Zyngier wrote: > On a system without KVM_COMPAT, we prevent IOCTLs from being issued > by a compat task. Although this prevents most silly things from > happening, it can still confuse a 32bit userspace that is able > to open the kvm device (the qemu test suite seems to be pretty > mad with this behaviour). > > Take a more radical approach and return a -ENODEV to the compat > task. > > Reported-by: Peter Maydell > Signed-off-by: Marc Zyngier > --- > virt/kvm/kvm_main.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 543024c7a87f..1243e48dc717 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -122,7 +122,13 @@ static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl, > #else > static long kvm_no_compat_ioctl(struct file *file, unsigned int ioctl, > unsigned long arg) { return -EINVAL; } > -#define KVM_COMPAT(c) .compat_ioctl = kvm_no_compat_ioctl > + > +static int kvm_no_compat_open(struct inode *inode, struct file *file) > +{ > + return is_compat_task() ? -ENODEV : 0; > +} > +#define KVM_COMPAT(c) .compat_ioctl = kvm_no_compat_ioctl, \ Do we still need compat_ioctl if open never succeeds? > + .open = kvm_no_compat_open > #endif > static int hardware_enable_all(void); > static void hardware_disable_all(void); >