From patchwork Wed Aug 16 17:30:19 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mimi Zohar X-Patchwork-Id: 9904379 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D64AC603B5 for ; Wed, 16 Aug 2017 17:31:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C157F28A58 for ; Wed, 16 Aug 2017 17:31:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B5F9E28A5B; Wed, 16 Aug 2017 17:31:08 +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=-6.9 required=2.0 tests=BAYES_00,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 11CAE28A3A for ; Wed, 16 Aug 2017 17:31:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751844AbdHPRar (ORCPT ); Wed, 16 Aug 2017 13:30:47 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:42058 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752031AbdHPRao (ORCPT ); Wed, 16 Aug 2017 13:30:44 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v7GHSmDY053523 for ; Wed, 16 Aug 2017 13:30:44 -0400 Received: from e23smtp03.au.ibm.com (e23smtp03.au.ibm.com [202.81.31.145]) by mx0a-001b2d01.pphosted.com with ESMTP id 2ccnyfh5bk-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 16 Aug 2017 13:30:44 -0400 Received: from localhost by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Thu, 17 Aug 2017 03:30:39 +1000 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay08.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v7GHUdwU41418864; Thu, 17 Aug 2017 03:30:39 +1000 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v7GHUcKN014732; Thu, 17 Aug 2017 03:30:39 +1000 Received: from localhost.localdomain.com ([9.80.83.117]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id v7GHUNh8014102; Thu, 17 Aug 2017 03:30:35 +1000 From: Mimi Zohar To: Christoph Hellwig , Al Viro Cc: Jan Kara , Jeff Layton , Mimi Zohar , linux-fsdevel@vger.kernel.org, linux-ima-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org Subject: [RFC PATCH 3/4] security: define a new LSM sb_post_remount hook Date: Wed, 16 Aug 2017 13:30:19 -0400 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1502904620-20075-1-git-send-email-zohar@linux.vnet.ibm.com> References: <1502904620-20075-1-git-send-email-zohar@linux.vnet.ibm.com> X-TM-AS-MML: disable x-cbid: 17081617-0008-0000-0000-0000015379BD X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17081617-0009-0000-0000-000009863C98 Message-Id: <1502904620-20075-4-git-send-email-zohar@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-08-16_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1708160288 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Allow LSMs to compare the previous and new mount flags. This patch defines a new LSM hook named security_sb_post_remount. Signed-off-by: Mimi Zohar --- fs/namespace.c | 3 +++ include/linux/lsm_hooks.h | 9 +++++++++ include/linux/security.h | 8 ++++++++ security/security.c | 7 +++++++ 4 files changed, 27 insertions(+) diff --git a/fs/namespace.c b/fs/namespace.c index a7fa13f422ad..e6f4ea9a1008 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2228,6 +2228,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags, int err; struct super_block *sb = path->mnt->mnt_sb; struct mount *mnt = real_mount(path->mnt); + unsigned long prev_sb_flags = sb->s_flags; if (!check_mnt(mnt)) return -EINVAL; @@ -2279,6 +2280,8 @@ static int do_remount(struct path *path, int flags, int mnt_flags, mnt->mnt.mnt_flags = mnt_flags; touch_mnt_namespace(mnt->mnt_ns); unlock_mount_hash(); + + security_sb_post_remount(sb, prev_sb_flags, path); } up_write(&sb->s_umount); return err; diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index c3ecea0d0dca..e940dc43786c 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -123,6 +123,11 @@ * @sb superblock being remounted * @data contains the filesystem-specific data. * Return 0 if permission is granted. + * @sb_post_remount: + * Allow comparison between new and previous mount flags. + * @sb superblock being remounted + * @prev_sb_flags previous mount flags + * @path contains the path for mount point object. * @sb_umount: * Check permission before the @mnt file system is unmounted. * @mnt contains the mounted file system. @@ -1395,6 +1400,9 @@ union security_list_options { void (*sb_free_security)(struct super_block *sb); int (*sb_copy_data)(char *orig, char *copy); int (*sb_remount)(struct super_block *sb, void *data); + void (*sb_post_remount)(const struct super_block *sb, + const unsigned long prev_sb_flags, + const struct path *path); int (*sb_kern_mount)(struct super_block *sb, int flags, void *data); int (*sb_show_options)(struct seq_file *m, struct super_block *sb); int (*sb_statfs)(struct dentry *dentry); @@ -1717,6 +1725,7 @@ struct security_hook_heads { struct list_head sb_free_security; struct list_head sb_copy_data; struct list_head sb_remount; + struct list_head sb_post_remount; struct list_head sb_kern_mount; struct list_head sb_show_options; struct list_head sb_statfs; diff --git a/include/linux/security.h b/include/linux/security.h index 4acdaae7aa04..fa963a870a84 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -237,6 +237,9 @@ int security_sb_alloc(struct super_block *sb); void security_sb_free(struct super_block *sb); int security_sb_copy_data(char *orig, char *copy); int security_sb_remount(struct super_block *sb, void *data); +void security_sb_post_remount(const struct super_block *sb, + unsigned long prev_sb_flags, + const struct path *path); int security_sb_kern_mount(struct super_block *sb, int flags, void *data); int security_sb_show_options(struct seq_file *m, struct super_block *sb); int security_sb_statfs(struct dentry *dentry); @@ -565,6 +568,11 @@ static inline int security_sb_remount(struct super_block *sb, void *data) return 0; } +static inline void security_sb_post_remount(const struct super_block *sb, + unsigned long prev_sb_flags, + const struct path *path)) +{ } + static inline int security_sb_kern_mount(struct super_block *sb, int flags, void *data) { return 0; diff --git a/security/security.c b/security/security.c index 79111141b383..7981ad9019c9 100644 --- a/security/security.c +++ b/security/security.c @@ -377,6 +377,13 @@ int security_sb_remount(struct super_block *sb, void *data) return call_int_hook(sb_remount, 0, sb, data); } +void security_sb_post_remount(const struct super_block *sb, + unsigned long prev_sb_flags, + const struct path *path) +{ + call_void_hook(sb_post_remount, sb, prev_sb_flags, path); +} + int security_sb_kern_mount(struct super_block *sb, int flags, void *data) { return call_int_hook(sb_kern_mount, 0, sb, flags, data);