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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 771EBC43441 for ; Tue, 27 Nov 2018 11:53:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 46C1C2082F for ; Tue, 27 Nov 2018 11:53:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 46C1C2082F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-integrity-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728414AbeK0Wu4 (ORCPT ); Tue, 27 Nov 2018 17:50:56 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:49376 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726494AbeK0Wu4 (ORCPT ); Tue, 27 Nov 2018 17:50:56 -0500 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wARBhw43092091 for ; Tue, 27 Nov 2018 06:53:16 -0500 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0a-001b2d01.pphosted.com with ESMTP id 2p149bbcv3-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 27 Nov 2018 06:53:16 -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) Tue, 27 Nov 2018 11:53:12 -0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id wARBrBPq3604926 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 27 Nov 2018 11:53:11 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7310DA4069; Tue, 27 Nov 2018 11:53:11 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B0E04A4054; Tue, 27 Nov 2018 11:53:10 +0000 (GMT) Received: from localhost.localdomain (unknown [9.80.104.65]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 27 Nov 2018 11:53:10 +0000 (GMT) Subject: Re: [PATCH 1/3] ima-avm-utils: Fix hash buffer overflow in verify_evm From: Mimi Zohar To: Vitaly Chikunov , Mimi Zohar , Dmitry Kasatkin , linux-integrity@vger.kernel.org Date: Tue, 27 Nov 2018 06:52:59 -0500 In-Reply-To: <20181126043953.1126-1-vt@altlinux.org> References: <20181126043953.1126-1-vt@altlinux.org> 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: 18112711-0028-0000-0000-0000032229AF X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18112711-0029-0000-0000-000023DE3237 Message-Id: <1543319579.3902.129.camel@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-11-27_10:,, 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-1811270104 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Mon, 2018-11-26 at 07:39 +0300, Vitaly Chikunov wrote: > Commit ae1319eeabd6 ("Remove hardcoding of SHA1 in EVM signatures") > introduces overflow of 20 byte buffer on the stack while calculating evm > hash. Also, invalid hash length is passed to the underlying verification > function. This prevents any non-SHA1 hashes from being properly > validated using evmctl. > > Signed-off-by: Vitaly Chikunov Thanks!  To prevent this sort of bug from recurring, it would be nice if the maximum digest size would be defined once and used. Mimi > --- > src/evmctl.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/src/evmctl.c b/src/evmctl.c > index 1b46d58..94d7ab1 100644 > --- a/src/evmctl.c > +++ b/src/evmctl.c > @@ -55,6 +55,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -760,13 +761,15 @@ static int cmd_sign_evm(struct command *cmd) > > static int verify_evm(const char *file) > { > - unsigned char hash[20]; > + unsigned char hash[64]; > unsigned char sig[1024]; > + int mdlen; > int len; > > - len = calc_evm_hash(file, hash); > - if (len <= 1) > - return len; > + mdlen = calc_evm_hash(file, hash); > + assert(mdlen <= sizeof(hash)); > + if (mdlen <= 1) > + return mdlen; > > len = lgetxattr(file, "security.evm", sig, sizeof(sig)); > if (len < 0) { > @@ -779,7 +782,7 @@ static int verify_evm(const char *file) > return -1; > } > > - return verify_hash(file, hash, sizeof(hash), sig + 1, len - 1); > + return verify_hash(file, hash, mdlen, sig + 1, len - 1); > } > > static int cmd_verify_evm(struct command *cmd)