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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 31 Jan 2020 14:50:36 -0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06avi18626390.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 00VEnh0Z41615722 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 31 Jan 2020 14:49:43 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BB3BC11C04A; Fri, 31 Jan 2020 14:50:35 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E76FD11C052; Fri, 31 Jan 2020 14:50:34 +0000 (GMT) Received: from localhost.localdomain (unknown [9.85.193.32]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 31 Jan 2020 14:50:34 +0000 (GMT) Subject: Re: [PATCH 7/8] ima: use ima_hash_algo for collision detection in the measurement list From: Mimi Zohar To: Roberto Sassu , "jarkko.sakkinen@linux.intel.com" , "james.bottomley@hansenpartnership.com" , "linux-integrity@vger.kernel.org" Cc: "linux-security-module@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Silviu Vlasceanu Date: Fri, 31 Jan 2020 09:50:34 -0500 In-Reply-To: References: <20200127170443.21538-1-roberto.sassu@huawei.com> <20200127170443.21538-8-roberto.sassu@huawei.com> <1580423169.6104.18.camel@linux.ibm.com> <44c1b3f6d3fe414e914317ef8e5c6f8f@huawei.com> <1580480525.6104.88.camel@linux.ibm.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: 20013114-0028-0000-0000-000003D64945 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20013114-0029-0000-0000-0000249A9BA2 Message-Id: <1580482234.6104.92.camel@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-01-31_03:2020-01-31,2020-01-31 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 lowpriorityscore=0 spamscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 mlxlogscore=999 adultscore=0 clxscore=1015 mlxscore=0 phishscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1911200001 definitions=main-2001310125 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2020-01-31 at 14:41 +0000, Roberto Sassu wrote: > I thought that using a stronger algorithm for hash collision detection but > doing remote attestation with the weaker would not bring additional value. > > If there is a hash collision on SHA1, an attacker can still replace the data of > one of the two entries in the measurement list with the data of the other > without being detected (without additional countermeasures). > > If the verifier additionally checks for duplicate template digests, he could > detect the attack (IMA would not add a new measurement entry with the > same template digest of previous entries). > > Ok, I will use ima_hash_algo for hash collision detection. Thanks! Mimi