From patchwork Tue May 5 17:30:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mimi Zohar X-Patchwork-Id: 11529691 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5449C14C0 for ; Tue, 5 May 2020 17:31:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FECD20721 for ; Tue, 5 May 2020 17:31:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730577AbgEERbJ (ORCPT ); Tue, 5 May 2020 13:31:09 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:56558 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729199AbgEERbJ (ORCPT ); Tue, 5 May 2020 13:31:09 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 045H2DC3174902; Tue, 5 May 2020 13:31:06 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 30s1sx6e6a-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 05 May 2020 13:31:05 -0400 Received: from m0098419.ppops.net (m0098419.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 045HQ1gP047636; Tue, 5 May 2020 13:31:05 -0400 Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0b-001b2d01.pphosted.com with ESMTP id 30s1sx6e5e-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 05 May 2020 13:31:05 -0400 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.0.27/8.16.0.27) with SMTP id 045HKTBc015153; Tue, 5 May 2020 17:31:03 GMT Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by ppma03ams.nl.ibm.com with ESMTP id 30s0g5qfa8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 05 May 2020 17:31:03 +0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 045HV1kV1835350 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 5 May 2020 17:31:01 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 04690A4062; Tue, 5 May 2020 17:31:01 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BBEE3A4060; Tue, 5 May 2020 17:30:59 +0000 (GMT) Received: from localhost.localdomain (unknown [9.85.161.225]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 5 May 2020 17:30:59 +0000 (GMT) From: Mimi Zohar To: linux-integrity@vger.kernel.org Cc: Casey Schaufler , Mimi Zohar , Jann Horn , Stephen Smalley , Eric Biggers , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v1] ima: verify mprotect change is consistent with mmap policy Date: Tue, 5 May 2020 13:30:45 -0400 Message-Id: <1588699845-6196-1-git-send-email-zohar@linux.ibm.com> X-Mailer: git-send-email 2.7.5 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.676 definitions=2020-05-05_09:2020-05-04,2020-05-05 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 malwarescore=0 phishscore=0 adultscore=0 impostorscore=0 mlxlogscore=915 bulkscore=0 clxscore=1015 suspectscore=3 mlxscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005050129 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: Files can be mmap'ed read/write and later changed to execute to circumvent IMA's mmap appraise policy rules. Due to locking issues (mmap semaphore would be taken prior to i_mutex), files can not be measured or appraised at this point. Eliminate this integrity gap, by denying the mprotect PROT_EXECUTE change, if an mmap appraise policy rule exists. On mprotect change success, return 0. On failure, return -EACESS. Signed-off-by: Mimi Zohar Reviewed-by: Lakshmi Ramasubramanian --- Changelog v1: - Reverse tests to remove code indentation. (Lakshmi Ramasubramanian) - General code cleanup, including adding comments. include/linux/ima.h | 7 ++++++ security/integrity/ima/ima_main.c | 51 +++++++++++++++++++++++++++++++++++++++ security/security.c | 7 +++++- 3 files changed, 64 insertions(+), 1 deletion(-) diff --git a/include/linux/ima.h b/include/linux/ima.h index aefe758f4466..9164e1534ec9 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -18,6 +18,7 @@ extern int ima_file_check(struct file *file, int mask); extern void ima_post_create_tmpfile(struct inode *inode); extern void ima_file_free(struct file *file); extern int ima_file_mmap(struct file *file, unsigned long prot); +extern int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot); extern int ima_load_data(enum kernel_load_data_id id); extern int ima_read_file(struct file *file, enum kernel_read_file_id id); extern int ima_post_read_file(struct file *file, void *buf, loff_t size, @@ -70,6 +71,12 @@ static inline int ima_file_mmap(struct file *file, unsigned long prot) return 0; } +static inline int ima_file_mprotect(struct vm_area_struct *vma, + unsigned long prot) +{ + return 0; +} + static inline int ima_load_data(enum kernel_load_data_id id) { return 0; diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index f96f151294e6..800fb3bba418 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -394,6 +394,57 @@ int ima_file_mmap(struct file *file, unsigned long prot) } /** + * ima_file_mprotect - based on policy, limit mprotect change + * @prot: contains the protection that will be applied by the kernel. + * + * Files can be mmap'ed read/write and later changed to execute to circumvent + * IMA's mmap appraisal policy rules. Due to locking issues (mmap semaphore + * would be taken before i_mutex), files can not be measured or appraised at + * this point. Eliminate this integrity gap by denying the mprotect + * PROT_EXECUTE change, if an mmap appraise policy rule exists. + * + * On mprotect change success, return 0. On failure, return -EACESS. + */ +int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot) +{ + struct ima_template_desc *template; + struct file *file = vma->vm_file; + char filename[NAME_MAX]; + char *pathbuf = NULL; + const char *pathname = NULL; + struct inode *inode; + int result = 0; + int action; + u32 secid; + int pcr; + + /* Is mprotect making an mmap'ed file executable? */ + if (!vma->vm_file || !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC)) + return 0; + + security_task_getsecid(current, &secid); + inode = file_inode(vma->vm_file); + action = ima_get_action(inode, current_cred(), secid, MAY_EXEC, + MMAP_CHECK, &pcr, &template, 0); + + /* Is the mmap'ed file in policy? */ + if (!(action & (IMA_MEASURE | IMA_APPRAISE_SUBMASK))) + return 0; + + if (action & IMA_APPRAISE_SUBMASK) + result = -EPERM; + + file = vma->vm_file; + pathname = ima_d_path(&file->f_path, &pathbuf, filename); + integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, pathname, + "collect_data", "failed-mprotect", result, 0); + if (pathbuf) + __putname(pathbuf); + + return result; +} + +/** * ima_bprm_check - based on policy, collect/store measurement. * @bprm: contains the linux_binprm structure * diff --git a/security/security.c b/security/security.c index 7fed24b9d57e..dd0917c5bfe9 100644 --- a/security/security.c +++ b/security/security.c @@ -1512,7 +1512,12 @@ int security_mmap_addr(unsigned long addr) int security_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot, unsigned long prot) { - return call_int_hook(file_mprotect, 0, vma, reqprot, prot); + int ret; + + ret = call_int_hook(file_mprotect, 0, vma, reqprot, prot); + if (ret) + return ret; + return ima_file_mprotect(vma, prot); } int security_file_lock(struct file *file, unsigned int cmd)