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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 19 Mar 2019 17:05:33 -0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x2JH5ZVi59375796 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 19 Mar 2019 17:05:35 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EA8C34C044; Tue, 19 Mar 2019 17:05:34 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7CD024C040; Tue, 19 Mar 2019 17:05:34 +0000 (GMT) Received: from dhcp-9-31-103-153.watson.ibm.com (unknown [9.31.103.153]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 19 Mar 2019 17:05:34 +0000 (GMT) Subject: Re: Should mprotect(..., PROT_EXEC) be checked by IMA? From: Mimi Zohar To: Igor Zhbanov , linux-integrity@vger.kernel.org Date: Tue, 19 Mar 2019 13:05:34 -0400 In-Reply-To: <84145490-6f70-214f-8241-42d556590240@omprussia.ru> References: <1552945715.8658.299.camel@linux.ibm.com> <452752df-98f9-c361-878a-5df84ab36847@omprussia.ru> <1552994559.4899.26.camel@linux.ibm.com> <84145490-6f70-214f-8241-42d556590240@omprussia.ru> 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: 19031917-0012-0000-0000-00000304CDE7 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19031917-0013-0000-0000-0000213BDDF6 Message-Id: <1553015134.4899.82.camel@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-19_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=62 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-1903190125 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Tue, 2019-03-19 at 15:19 +0300, Igor Zhbanov wrote: > On 19.03.2019 14:22, Mimi Zohar wrote: > > On Tue, 2019-03-19 at 10:50 +0300, Igor Zhbanov wrote: > >> Hi Mimi, > >> > >> I guess similar to SELinux function: > > [snip] > > > > Remember IMA relies on LSMs for mandatory access control(MAC).  IMA > > measures, audits, and enforces file integrity. > > Yes. But LSM will not check integrity of the file mmaped for read. Nor does > IMA. > Ok, so we can start there and modify the existing ima_file_mmap() to verify file signatures that are being mmap'ed read.  The question will then become what to do with mprotect write and execute. > >> The structure vm_area_struct has a pointer vm_file pointing to mapped file > >> so it could be used what file's xattrs to check. > > > > That's fine for when there is a file descriptor, but the file > > descriptor could have been closed.  (Refer to the mmap manpage.) > > Can it be checked? > > I think that checking the integrity at least in the case when the file is > still open is better than not checking at all. Because as I said it would > be possible to use mmap+mprotect to bypass IMA for shared libraries checking. And what would you do with the mprotect without a file descriptor? The mmap signature verification status is cached in the iint, based on the inode.  I think whatever solution will need to be able to access this cached information. Mimi