From patchwork Mon May 6 16:57:03 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mimi Zohar X-Patchwork-Id: 10931613 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9FD891515 for ; Mon, 6 May 2019 16:58:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8F56128872 for ; Mon, 6 May 2019 16:58:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 82F6828876; Mon, 6 May 2019 16:58:10 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2718B28872 for ; Mon, 6 May 2019 16:58:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726608AbfEFQ6J (ORCPT ); Mon, 6 May 2019 12:58:09 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:39576 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726985AbfEFQ5y (ORCPT ); Mon, 6 May 2019 12:57:54 -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 x46GqQWp176503 for ; Mon, 6 May 2019 12:57:53 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0b-001b2d01.pphosted.com with ESMTP id 2saqrh35s8-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 06 May 2019 12:57:53 -0400 Received: from localhost by e06smtp02.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) Mon, 6 May 2019 17:57:49 +0100 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x46Gvmhl62586934 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 6 May 2019 16:57:48 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 19BC9A4040; Mon, 6 May 2019 16:57:48 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 34EC3A404D; Mon, 6 May 2019 16:57:47 +0000 (GMT) Received: from localhost.ibm.com (unknown [9.80.95.145]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 6 May 2019 16:57:47 +0000 (GMT) From: Mimi Zohar To: linux-integrity@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Igor Zhbanov , Jordan Glover , Al Viro , Mimi Zohar Subject: [PATCH 2/3] ima: prevent a file already mmap'ed write to be mmap'ed execute Date: Mon, 6 May 2019 12:57:03 -0400 X-Mailer: git-send-email 2.7.5 In-Reply-To: <1557161824-6623-1-git-send-email-zohar@linux.ibm.com> References: <1557161824-6623-1-git-send-email-zohar@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 19050616-0008-0000-0000-000002E3DF89 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19050616-0009-0000-0000-0000225058CB Message-Id: <1557161824-6623-3-git-send-email-zohar@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-06_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 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-1905060144 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The kernel calls deny_write_access() to prevent a file already opened for write from being executed and also prevents files being executed from being opened for write. For some reason this does not extend to files being mmap'ed execute. From an IMA perspective, measuring/appraising the integrity of a file being mmap'ed execute, without first making sure the file cannot be modified, makes no sense. This patch prevents files, in policy, already mmap'ed write, from being mmap'ed execute. Signed-off-by: Mimi Zohar --- security/integrity/ima/ima_main.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 357edd140c09..ae77d13cb43c 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -72,6 +72,27 @@ static int __init hash_setup(char *str) } __setup("ima_hash=", hash_setup); +/* Prevent mmap'ing a file execute that is already mmap'ed write */ +static int mmap_violation_check(enum ima_hooks func, struct file *file, + char **pathbuf, const char **pathname, + char *filename) +{ + struct inode *inode; + int rc = 0; + + if ((func == MMAP_CHECK) && mapping_writably_mapped(file->f_mapping)) { + rc = -ETXTBSY; + inode = file_inode(file); + + if (!*pathbuf) /* ima_rdwr_violation possibly pre-fetched */ + *pathname = ima_d_path(&file->f_path, pathbuf, + filename); + integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, *pathname, + "mmap_file", "mmapped_writers", rc, 0); + } + return rc; +} + /* * ima_rdwr_violation_check * @@ -270,8 +291,12 @@ static int process_measurement(struct file *file, const struct cred *cred, /* Nothing to do, just return existing appraised status */ if (!action) { - if (must_appraise) - rc = ima_get_cache_status(iint, func); + if (must_appraise) { + rc = mmap_violation_check(func, file, &pathbuf, + &pathname, filename); + if (!rc) + rc = ima_get_cache_status(iint, func); + } goto out_locked; } @@ -298,6 +323,9 @@ static int process_measurement(struct file *file, const struct cred *cred, rc = ima_appraise_measurement(func, iint, file, pathname, xattr_value, xattr_len); inode_unlock(inode); + + rc = mmap_violation_check(func, file, &pathbuf, &pathname, + filename); } if (action & IMA_AUDIT) ima_audit_measurement(iint, pathname);