From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751969AbeECBnO (ORCPT ); Wed, 2 May 2018 21:43:14 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:51088 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751861AbeECBnK (ORCPT ); Wed, 2 May 2018 21:43:10 -0400 Subject: Re: [PATCH] evm: Don't update hmacs in user ns mounts From: Mimi Zohar To: "Eric W. Biederman" Cc: linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, James Morris Date: Wed, 02 May 2018 21:43:03 -0400 In-Reply-To: <87r2mtybhf.fsf@xmission.com> References: <87r2mtybhf.fsf@xmission.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.5 (3.20.5-1.fc24) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18050301-0040-0000-0000-000004355780 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18050301-0041-0000-0000-0000263977BC Message-Id: <1525311783.3238.19.camel@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-03_01:,, 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=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1805030012 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2018-05-02 at 16:49 -0500, Eric W. Biederman wrote: > From: Seth Forshee > Date: Fri, 22 Dec 2017 15:32:35 +0100 > > The kernel should not calculate new hmacs for mounts done by > non-root users. Update evm_calc_hmac_or_hash() to refuse to > calculate new hmacs for mounts for non-init user namespaces. > > Cc: linux-integrity@vger.kernel.org > Cc: linux-security-module@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Cc: James Morris > Cc: Mimi Zohar > Cc: "Serge E. Hallyn" > Signed-off-by: Seth Forshee > Signed-off-by: Dongsu Park > Signed-off-by: Eric W. Biederman > --- > > Mimi this patch has been floating around for a while and it appears to > be the only piece missing from the vfs to make unprivileged mounts safe > (at least semantically). Do you want to merge this through your integrity > tree or should merge this through my userns tree? Matthew's EVM patches don't conflict with this change, so either way is fine. Mimi > > security/integrity/evm/evm_crypto.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > > diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c > index a46fba322340..facf9cdd577d 100644 > --- a/security/integrity/evm/evm_crypto.c > +++ b/security/integrity/evm/evm_crypto.c > @@ -200,7 +200,8 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry, > int size; > bool ima_present = false; > > - if (!(inode->i_opflags & IOP_XATTR)) > + if (!(inode->i_opflags & IOP_XATTR) || > + inode->i_sb->s_user_ns != &init_user_ns) > return -EOPNOTSUPP; > > desc = init_desc(type);