From patchwork Thu Mar 28 17:50:40 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 10875603 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 A72251708 for ; Thu, 28 Mar 2019 17:50:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9388528E8E for ; Thu, 28 Mar 2019 17:50:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9184128EDA; Thu, 28 Mar 2019 17:50:49 +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=-5.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, SUSPICIOUS_RECIPS,UNPARSEABLE_RELAY autolearn=unavailable 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 2FDA028F23 for ; Thu, 28 Mar 2019 17:50:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727606AbfC1Rur (ORCPT ); Thu, 28 Mar 2019 13:50:47 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:40288 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726453AbfC1Rur (ORCPT ); Thu, 28 Mar 2019 13:50:47 -0400 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x2SHnInj049215; Thu, 28 Mar 2019 17:50:44 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : from : to : cc : date : message-id : in-reply-to : references : mime-version : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=9mq463y6Fy+tnAy6EAF3waabQKAMjMyUGNNPLiFAWs8=; b=06/ipe6rPVPCmRT+ZDZ1UYm6lTddupzdsLbZKnyxxACsXOMVgVpbAqwVHWoOXiMGJm5K TBtsCl8fw8vRWdtMYTIo5Ooi8xDSsY6rl2/11GAH3q58pYxhznYZN1Vzz53wxcUBWCsL 0Q6+TB/he1b1fT2DL6djhk+Vj9AMCZn0fOqrtUCSt/NPENvnctzuHqpvfDrZRPddQs5o xP0dQlC2+i9gGmAoaOIwLHDB/XBtppbrHEjAu392Q7PuTER+K/ULqEmy3Bu6yak6Flnc 9SaA/mRSn3v2ZIb484gddpklZUrBJDrbh1w6dHOugyZ6V9TlDIBf7LFnW8GoZk9OolD0 oQ== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by aserp2130.oracle.com with ESMTP id 2re6g187wm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 17:50:43 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id x2SHogvP030296 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 17:50:43 GMT Received: from abhmp0020.oracle.com (abhmp0020.oracle.com [141.146.116.26]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x2SHogTt009429; Thu, 28 Mar 2019 17:50:42 GMT Received: from localhost (/10.159.234.216) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 28 Mar 2019 10:50:42 -0700 Subject: [PATCH 1/3] mm/fs: don't allow writes to immutable files From: "Darrick J. Wong" To: darrick.wong@oracle.com Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org Date: Thu, 28 Mar 2019 10:50:40 -0700 Message-ID: <155379544071.24796.11489520877297987568.stgit@magnolia> In-Reply-To: <155379543409.24796.5783716624820175068.stgit@magnolia> References: <155379543409.24796.5783716624820175068.stgit@magnolia> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9209 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=240 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903280117 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Darrick J. Wong The chattr manpage has this to say about immutable files: "A file with the 'i' attribute cannot be modified: it cannot be deleted or renamed, no link can be created to this file, most of the file's metadata can not be modified, and the file can not be opened in write mode." Once the flag is set, it is enforced for quite a few file operations, such as fallocate, fpunch, fzero, rm, touch, open, etc. However, we don't check for immutability when doing a write(), a PROT_WRITE mmap(), a truncate(), or a write to a previously established mmap. If a program has an open write fd to a file that the administrator subsequently marks immutable, the program still can change the file contents. Weird! The ability to write to an immutable file does not follow the manpage promise that immutable files cannot be modified. Worse yet it's inconsistent with the behavior of other syscalls which don't allow modifications of immutable files. Therefore, add the necessary checks to make the write, mmap, and truncate behavior consistent with what the manpage says and consistent with other syscalls on filesystems which support IMMUTABLE. Signed-off-by: Darrick J. Wong --- fs/attr.c | 13 ++++++------- mm/filemap.c | 3 +++ mm/memory.c | 3 +++ mm/mmap.c | 3 +++ 4 files changed, 15 insertions(+), 7 deletions(-) diff --git a/fs/attr.c b/fs/attr.c index d22e8187477f..1fcfdcc5b367 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -233,19 +233,18 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de WARN_ON_ONCE(!inode_is_locked(inode)); - if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) { - if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) - return -EPERM; - } + if (IS_IMMUTABLE(inode)) + return -EPERM; + + if ((ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) && + IS_APPEND(inode)) + return -EPERM; /* * If utimes(2) and friends are called with times == NULL (or both * times are UTIME_NOW), then we need to check for write permission */ if (ia_valid & ATTR_TOUCH) { - if (IS_IMMUTABLE(inode)) - return -EPERM; - if (!inode_owner_or_capable(inode)) { error = inode_permission(inode, MAY_WRITE); if (error) diff --git a/mm/filemap.c b/mm/filemap.c index d78f577baef2..9fed698f4c63 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3033,6 +3033,9 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from) loff_t count; int ret; + if (IS_IMMUTABLE(inode)) + return -EPERM; + if (!iov_iter_count(from)) return 0; diff --git a/mm/memory.c b/mm/memory.c index 47fe250307c7..c493db22413a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2148,6 +2148,9 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf) vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; + if (vmf->vma->vm_file && IS_IMMUTABLE(file_inode(vmf->vma->vm_file))) + return VM_FAULT_SIGBUS; + ret = vmf->vma->vm_ops->page_mkwrite(vmf); /* Restore original flags so that caller is not surprised */ vmf->flags = old_flags; diff --git a/mm/mmap.c b/mm/mmap.c index 41eb48d9b527..e49dcbeda461 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1394,6 +1394,9 @@ unsigned long do_mmap(struct file *file, unsigned long addr, if (!len) return -EINVAL; + if (file && IS_IMMUTABLE(file_inode(file))) + return -EPERM; + /* * Does the application expect PROT_READ to imply PROT_EXEC? * From patchwork Thu Mar 28 17:50:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 10875613 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 C3C6717E0 for ; Thu, 28 Mar 2019 17:50:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AF53328F8A for ; Thu, 28 Mar 2019 17:50:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id ACC2C28ED4; Thu, 28 Mar 2019 17:50:56 +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=-5.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, SUSPICIOUS_RECIPS,UNPARSEABLE_RELAY autolearn=unavailable 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 B9F3F28E7B for ; Thu, 28 Mar 2019 17:50:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727630AbfC1Rux (ORCPT ); Thu, 28 Mar 2019 13:50:53 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:48868 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726453AbfC1Rux (ORCPT ); Thu, 28 Mar 2019 13:50:53 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x2SHnFbH045222; Thu, 28 Mar 2019 17:50:51 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : from : to : cc : date : message-id : in-reply-to : references : mime-version : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=QWFkhrEj/UWEKTtDQrlQN9lEAI12q4qBRSWOWf5aE6A=; b=1kL5ci9A0ShDtplZSlWzGFRsQE+gk47tOhTWQtwBpLPMpXEd6hg00YAALT/cbvgPQpbD fnSRohTjoI7RLLX7CKrgTI9aua9FA4uJFerc9hLRPoWwzNvzaQ557M1MvW2SuN0QSHiq Vyv6ZN9Q4dbl+qZrZOwxPhv7HhjmXNaz2ZtZoW0G61gU0XjdtrVk5td4aFE4Dm3kpASy mt6FbLLqA9hg0d9ntBEfD8WZ6XGz4CW+JpUa8zclDrafj2kiZ4fYgAkdpwPhldW2dOCy H40mU8hGB9GJC0afxmCuLPONrqnh5JVL4/mPp3EdEBa2Q/7seZM2RFnjiFvzkC/yCPWr iQ== Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by userp2130.oracle.com with ESMTP id 2re6g1g6pg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 17:50:50 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id x2SHonoC029902 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 17:50:49 GMT Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x2SHonCl005937; Thu, 28 Mar 2019 17:50:49 GMT Received: from localhost (/10.159.234.216) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 28 Mar 2019 10:50:48 -0700 Subject: [PATCH 2/3] xfs: reset page mappings after setting immutable From: "Darrick J. Wong" To: darrick.wong@oracle.com Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org Date: Thu, 28 Mar 2019 10:50:47 -0700 Message-ID: <155379544747.24796.1807309281507099911.stgit@magnolia> In-Reply-To: <155379543409.24796.5783716624820175068.stgit@magnolia> References: <155379543409.24796.5783716624820175068.stgit@magnolia> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9209 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=3 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=704 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903280117 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Darrick J. Wong The chattr manpage has this to say about immutable files: "A file with the 'i' attribute cannot be modified: it cannot be deleted or renamed, no link can be created to this file, most of the file's metadata can not be modified, and the file can not be opened in write mode." This means that we need to flush the page cache when setting the immutable flag so that programs cannot continue to write to writable mappings. Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_ioctl.c | 63 +++++++++++++++++++++++++++++++++++----------------- 1 file changed, 43 insertions(+), 20 deletions(-) diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index 6ecdbb3af7de..2bd1c5ab5008 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -998,6 +998,37 @@ xfs_diflags_to_linux( #endif } +static int +xfs_ioctl_setattr_flush( + struct xfs_inode *ip, + int *join_flags) +{ + struct inode *inode = VFS_I(ip); + int error; + + if (S_ISDIR(inode->i_mode)) + return 0; + if ((*join_flags) & (XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL)) + return 0; + + /* lock, flush and invalidate mapping in preparation for flag change */ + xfs_ilock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); + error = filemap_write_and_wait(inode->i_mapping); + if (error) + goto out_unlock; + error = invalidate_inode_pages2(inode->i_mapping); + if (error) + goto out_unlock; + + *join_flags = XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL; + return 0; + +out_unlock: + xfs_iunlock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); + return error; + +} + static int xfs_ioctl_setattr_xflags( struct xfs_trans *tp, @@ -1067,7 +1098,6 @@ xfs_ioctl_setattr_dax_invalidate( { struct inode *inode = VFS_I(ip); struct super_block *sb = inode->i_sb; - int error; *join_flags = 0; @@ -1092,25 +1122,7 @@ xfs_ioctl_setattr_dax_invalidate( if (!(fa->fsx_xflags & FS_XFLAG_DAX) && !IS_DAX(inode)) return 0; - if (S_ISDIR(inode->i_mode)) - return 0; - - /* lock, flush and invalidate mapping in preparation for flag change */ - xfs_ilock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); - error = filemap_write_and_wait(inode->i_mapping); - if (error) - goto out_unlock; - error = invalidate_inode_pages2(inode->i_mapping); - if (error) - goto out_unlock; - - *join_flags = XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL; - return 0; - -out_unlock: - xfs_iunlock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); - return error; - + return xfs_ioctl_setattr_flush(ip, join_flags); } /* @@ -1356,6 +1368,17 @@ xfs_ioctl_setattr( if (code) goto error_free_dquots; + /* + * If we are trying to set immutable then flush everything to disk to + * force all writable memory mappings back through the pagefault + * handler. + */ + if (!IS_IMMUTABLE(VFS_I(ip)) && (fa->fsx_xflags & FS_XFLAG_IMMUTABLE)) { + code = xfs_ioctl_setattr_flush(ip, &join_flags); + if (code) + goto error_free_dquots; + } + tp = xfs_ioctl_setattr_get_trans(ip, join_flags); if (IS_ERR(tp)) { code = PTR_ERR(tp); From patchwork Thu Mar 28 17:50:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 10875621 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 26A5E1708 for ; Thu, 28 Mar 2019 17:51:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 137EE28E7B for ; Thu, 28 Mar 2019 17:51:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 11F2C28F83; Thu, 28 Mar 2019 17:51:01 +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=-5.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, SUSPICIOUS_RECIPS,UNPARSEABLE_RELAY autolearn=unavailable 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 BC81128E7B for ; Thu, 28 Mar 2019 17:51:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727666AbfC1Ru7 (ORCPT ); Thu, 28 Mar 2019 13:50:59 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:40522 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726453AbfC1Ru7 (ORCPT ); Thu, 28 Mar 2019 13:50:59 -0400 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x2SHnInl049215; Thu, 28 Mar 2019 17:50:57 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : from : to : cc : date : message-id : in-reply-to : references : mime-version : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=+SmhM0DmWKGoRrKZZ98M+WstE38ttkB52h8rDI9dPag=; b=m0S3I43+R6EcCGHOF8hLaM6kQEPuowPMGB6mnUSTClxHddNwVQ68LKEOfqrvL5rsCpY1 xvHYGYS608Y9qipKFy1V6wDLvZSOzgepfC90dr4FZnaN544BNKAB41Q053ovcaqLOG6a IFMcISAGKWZuRPjtlOUMhyA6rbl7d+/q6nVBjLV8AFrTmLgwR4GAP7iw1CT4/RM1qpm8 WVogSjJvNjHPeu5RR3uxAeNlJ1m/o0XHLrTIx1YlwVG2rQfE6+7q96mL+eKBAHln3Teu 4pyMNGymdq+8VExMVEY5tz5bMifZ/Kp7FrPoOkQlvpOttECejh1WtQARFRnMUbkMJpQ3 jA== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2130.oracle.com with ESMTP id 2re6g187xq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 17:50:57 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x2SHou87026449 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 17:50:56 GMT Received: from abhmp0017.oracle.com (abhmp0017.oracle.com [141.146.116.23]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x2SHotic006011; Thu, 28 Mar 2019 17:50:55 GMT Received: from localhost (/10.159.234.216) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 28 Mar 2019 10:50:55 -0700 Subject: [PATCH 3/3] xfs: don't allow most setxattr to immutable files From: "Darrick J. Wong" To: darrick.wong@oracle.com Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org Date: Thu, 28 Mar 2019 10:50:54 -0700 Message-ID: <155379545404.24796.5019142212767521955.stgit@magnolia> In-Reply-To: <155379543409.24796.5783716624820175068.stgit@magnolia> References: <155379543409.24796.5783716624820175068.stgit@magnolia> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9209 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=854 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903280117 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Darrick J. Wong The chattr manpage has this to say about immutable files: "A file with the 'i' attribute cannot be modified: it cannot be deleted or renamed, no link can be created to this file, most of the file's metadata can not be modified, and the file can not be opened in write mode." However, we don't actually check the immutable flag in the setattr code, which means that we can update project ids and extent size hints on supposedly immutable files. Therefore, reject a setattr call on an immutable file except for the case where we're trying to unset IMMUTABLE. Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_ioctl.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index 2bd1c5ab5008..9cf0bc0ae2bd 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -1067,6 +1067,14 @@ xfs_ioctl_setattr_xflags( !capable(CAP_LINUX_IMMUTABLE)) return -EPERM; + /* + * If immutable is set and we are not clearing it, we're not allowed + * to change anything else in the inode. + */ + if ((ip->i_d.di_flags & XFS_DIFLAG_IMMUTABLE) && + (fa->fsx_xflags & FS_XFLAG_IMMUTABLE)) + return -EPERM; + /* diflags2 only valid for v3 inodes. */ di_flags2 = xfs_flags2diflags2(ip, fa->fsx_xflags); if (di_flags2 && ip->i_d.di_version < 3)