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_2 autolearn=unavailable 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 A9315C33CB7 for ; Fri, 31 Jan 2020 14:22:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7FD06215A4 for ; Fri, 31 Jan 2020 14:22:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728730AbgAaOWR (ORCPT ); Fri, 31 Jan 2020 09:22:17 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:16610 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728752AbgAaOWO (ORCPT ); Fri, 31 Jan 2020 09:22:14 -0500 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 00VEKBdp118653 for ; Fri, 31 Jan 2020 09:22:13 -0500 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0a-001b2d01.pphosted.com with ESMTP id 2xvkxcm94n-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 31 Jan 2020 09:22:13 -0500 Received: from localhost by e06smtp07.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) Fri, 31 Jan 2020 14:22:07 -0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 00VEM61T52559894 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 31 Jan 2020 14:22:06 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C9C3DA4040; Fri, 31 Jan 2020 14:22:06 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F32F7A4057; Fri, 31 Jan 2020 14:22:05 +0000 (GMT) Received: from localhost.localdomain (unknown [9.85.193.32]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 31 Jan 2020 14:22:05 +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 09:22:05 -0500 In-Reply-To: <44c1b3f6d3fe414e914317ef8e5c6f8f@huawei.com> 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> 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: 8bit X-TM-AS-GCONF: 00 x-cbid: 20013114-0028-0000-0000-000003D6478B X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20013114-0029-0000-0000-0000249A99D3 Message-Id: <1580480525.6104.88.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 phishscore=0 malwarescore=0 bulkscore=0 mlxlogscore=999 impostorscore=0 mlxscore=0 lowpriorityscore=0 priorityscore=1501 adultscore=0 spamscore=0 suspectscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1911200001 definitions=main-2001310123 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Fri, 2020-01-31 at 14:02 +0000, Roberto Sassu wrote: > > -----Original Message----- > > From: linux-integrity-owner@vger.kernel.org [mailto:linux-integrity- > > owner@vger.kernel.org] On Behalf Of Mimi Zohar > > Sent: Thursday, January 30, 2020 11:26 PM > > 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 > > Subject: Re: [PATCH 7/8] ima: use ima_hash_algo for collision detection in > > the measurement list > > > > On Mon, 2020-01-27 at 18:04 +0100, Roberto Sassu wrote: > > > Before calculating a digest for each PCR bank, collisions were detected > > > with a SHA1 digest. This patch includes ima_hash_algo among the > > algorithms > > > used to calculate the template digest and checks collisions on that digest. > > > > > > Signed-off-by: Roberto Sassu > > > > Definitely needed to protect against a sha1 collision attack. > > > > > > > > > > > > diff --git a/security/integrity/ima/ima_api.c > > b/security/integrity/ima/ima_api.c > > > index ebaf0056735c..a9bb45de6db9 100644 > > > --- a/security/integrity/ima/ima_api.c > > > +++ b/security/integrity/ima/ima_api.c > > > @@ -51,7 +51,7 @@ int ima_alloc_init_template(struct ima_event_data > > *event_data, > > > if (!*entry) > > > return -ENOMEM; > > > > > > - (*entry)->digests = kcalloc(ima_tpm_chip->nr_allocated_banks + 1, > > > + (*entry)->digests = kcalloc(ima_tpm_chip->nr_allocated_banks + 2, > > > sizeof(*(*entry)->digests), GFP_NOFS); > > > if (!(*entry)->digests) { > > > result = -ENOMEM; > > > > I would prefer not having to allocate and use "nr_allocated_banks + 1" > > everywhere, but I understand the need for it.  I'm not sure this patch > > warrants allocating +2.  Perhaps, if a TPM bank doesn't exist for the > > IMA default hash algorithm, use a different algorithm or, worst case, > > continue using the ima_sha1_idx. > > We could introduce a new option called ima_hash_algo_tpm to specify > the algorithm of an allocated bank. We can use this for boot_aggregate > and hash collision detection. I don't think that would work in the case where the IMA default hash is set to sha256, but the system has a TPM 1.2 chip.  We would be left using SHA1 for the file hash collision detection. With my suggestion of defining an "extra" variable, I kind of back tracked here.  There are two problems that I'm trying to address - hard coding the number of additional "banks" and unnecessarily allocating more memory than necessary.  By pre-walking the list, calculating the "extra" banks, you'll resolve both issues. Mimi