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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 D104BC04E84 for ; Tue, 28 May 2019 19:27:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B7DF520717 for ; Tue, 28 May 2019 19:27:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727858AbfE1T1g (ORCPT ); Tue, 28 May 2019 15:27:36 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:47014 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727795AbfE1T1f (ORCPT ); Tue, 28 May 2019 15:27:35 -0400 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x4SJOrx5056837 for ; Tue, 28 May 2019 15:27:34 -0400 Received: from e32.co.us.ibm.com (e32.co.us.ibm.com [32.97.110.150]) by mx0b-001b2d01.pphosted.com with ESMTP id 2ss94bdagp-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 28 May 2019 15:27:34 -0400 Received: from localhost by e32.co.us.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) Tue, 28 May 2019 20:27:28 +0100 Received: from b03ledav005.gho.boulder.ibm.com (b03ledav005.gho.boulder.ibm.com [9.17.130.236]) by b03cxnp08025.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x4SJRRNP22282730 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 28 May 2019 19:27:27 GMT Received: from b03ledav005.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0C0A6BE053; Tue, 28 May 2019 19:27:27 +0000 (GMT) Received: from b03ledav005.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D76FDBE058; Tue, 28 May 2019 19:27:22 +0000 (GMT) Received: from morokweng.localdomain (unknown [9.85.218.160]) by b03ledav005.gho.boulder.ibm.com (Postfix) with ESMTPS; Tue, 28 May 2019 19:27:22 +0000 (GMT) References: <20190418035120.2354-1-bauerman@linux.ibm.com> <20190418035120.2354-10-bauerman@linux.ibm.com> <1557835765.4139.9.camel@linux.ibm.com> User-agent: mu4e 1.0; emacs 26.2 From: Thiago Jung Bauermann To: Mimi Zohar Cc: linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Dmitry Kasatkin , James Morris , "Serge E. Hallyn" , David Howells , David Woodhouse , Jessica Yu , Herbert Xu , "David S. Miller" , Jonathan Corbet , "AKASHI\, Takahiro" Subject: Re: [PATCH v10 09/12] ima: Implement support for module-style appended signatures In-reply-to: <1557835765.4139.9.camel@linux.ibm.com> Date: Tue, 28 May 2019 16:27:17 -0300 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 19052819-0004-0000-0000-000015154B13 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00011176; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000286; SDB=6.01209921; UDB=6.00635635; IPR=6.00990951; MB=3.00027089; MTD=3.00000008; XFM=3.00000015; UTC=2019-05-28 19:27:32 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19052819-0005-0000-0000-00008BD76A03 Message-Id: <87y32q5qi2.fsf@morokweng.localdomain> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-28_09:,, 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=8.0.1-1810050000 definitions=main-1905280121 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org Mimi Zohar writes: > Hi Thiago, > > On Thu, 2019-04-18 at 00:51 -0300, Thiago Jung Bauermann wrote: >> >> @@ -326,6 +356,10 @@ int ima_appraise_measurement(enum ima_hooks func, >> case INTEGRITY_UNKNOWN: >> break; >> case INTEGRITY_NOXATTRS:/* No EVM protected xattrs. */ >> +/* It's fine not to have xattrs when using a modsig. */ >> +if (try_modsig) >> +break; >> +/* fall through */ >> case INTEGRITY_NOLABEL:/* No security.evm xattr. */ >> cause = "missing-HMAC"; >> goto out; >> @@ -340,6 +374,14 @@ int ima_appraise_measurement(enum ima_hooks func, >> rc = xattr_verify(func, iint, xattr_value, xattr_len, &status, >> &cause); >> >> +/* >> + * If we have a modsig and either no imasig or the imasig's key isn't >> + * known, then try verifying the modsig. >> + */ >> +if (status != INTEGRITY_PASS && try_modsig && >> + (!xattr_value || rc == -ENOKEY)) >> +rc = modsig_verify(func, modsig, &status, &cause); > > EVM protects other security xattrs, not just security.ima, if they > exist. As a result, evm_verifyxattr() could pass based on the other > security xattrs. Indeed! It doesn't make sense to test for status != INTEGRITY_PASS here. Not sure what I was thinking. Thanks for spotting it. With your other comments about this if clause, this code now reads: /* * If we have a modsig and either no imasig or the imasig's key isn't * known, then try verifying the modsig. */ if (try_modsig && (!xattr_value || xattr_value->type == IMA_XATTR_DIGEST_NG || rc == -ENOKEY)) rc = modsig_verify(func, modsig, &status, &cause); -- Thiago Jung Bauermann IBM Linux Technology Center