From patchwork Wed Dec 12 08:17:09 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= X-Patchwork-Id: 10725683 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 37D0291E for ; Wed, 12 Dec 2018 08:33:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 29C4C27165 for ; Wed, 12 Dec 2018 08:33:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1D67F2852D; Wed, 12 Dec 2018 08:33:48 +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 A8D2127165 for ; Wed, 12 Dec 2018 08:33:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726809AbeLLIdr (ORCPT ); Wed, 12 Dec 2018 03:33:47 -0500 Received: from smtp-sh2.infomaniak.ch ([128.65.195.6]:55862 "EHLO smtp-sh2.infomaniak.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726242AbeLLIdq (ORCPT ); Wed, 12 Dec 2018 03:33:46 -0500 X-Greylist: delayed 942 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Dec 2018 03:33:45 EST Received: from smtp7.infomaniak.ch (smtp7.infomaniak.ch [83.166.132.30]) by smtp-sh.infomaniak.ch (8.14.5/8.14.5) with ESMTP id wBC8Hjjk022496 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 12 Dec 2018 09:17:45 +0100 Received: from localhost (ns3096276.ip-94-23-54.eu [94.23.54.103]) (authenticated bits=0) by smtp7.infomaniak.ch (8.14.5/8.14.5) with ESMTP id wBC8HgY8061207; Wed, 12 Dec 2018 09:17:43 +0100 From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: linux-kernel@vger.kernel.org Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Al Viro , James Morris , Jonathan Corbet , Kees Cook , Matthew Garrett , Michael Kerrisk , =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Mimi Zohar , =?utf-8?q?Philippe_Tr=C3=A9buchet?= , Shuah Khan , Thibaut Sautereau , Vincent Strubel , Yves-Alexis Perez , kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [RFC PATCH v1 2/5] fs: Add a MAY_EXECMOUNT flag to infer the noexec mount propertie Date: Wed, 12 Dec 2018 09:17:09 +0100 Message-Id: <20181212081712.32347-3-mic@digikod.net> X-Mailer: git-send-email 2.20.0.rc2 In-Reply-To: <20181212081712.32347-1-mic@digikod.net> References: <20181212081712.32347-1-mic@digikod.net> MIME-Version: 1.0 X-Antivirus: Dr.Web (R) for Unix mail servers drweb plugin ver.6.0.2.8 X-Antivirus-Code: 0x100000 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP An LSM doesn't get path information related to an access request to open an inode. This new (internal) MAY_EXECMOUNT flag enables an LSM to check if the underlying mount point of an inode is marked as executable. This is useful to implement a security policy taking advantage of the noexec mount option. This flag is set according to path_noexec(), which checks if a mount point is mounted with MNT_NOEXEC or if the underlying superblock is SB_I_NOEXEC. Signed-off-by: Mickaël Salaün Reviewed-by: Philippe Trébuchet Reviewed-by: Thibaut Sautereau Cc: Al Viro Cc: Kees Cook Cc: Mickaël Salaün --- fs/namei.c | 2 ++ include/linux/fs.h | 2 ++ 2 files changed, 4 insertions(+) diff --git a/fs/namei.c b/fs/namei.c index 0cab6494978c..de4f33b3f464 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2970,6 +2970,8 @@ static int may_open(const struct path *path, int acc_mode, int flag) break; } + /* Pass the mount point executability. */ + acc_mode |= path_noexec(path) ? 0 : MAY_EXECMOUNT; error = inode_permission(inode, MAY_OPEN | acc_mode); if (error) return error; diff --git a/include/linux/fs.h b/include/linux/fs.h index 584c9329ad78..083a31b8068e 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -96,6 +96,8 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset, #define MAY_NOT_BLOCK 0x00000080 /* the inode is opened with O_MAYEXEC */ #define MAY_OPENEXEC 0x00000100 +/* the mount point is marked as executable */ +#define MAY_EXECMOUNT 0x00000200 /* * flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond