From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E25FC48BD3 for ; Wed, 26 Jun 2019 16:32:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D780120665 for ; Wed, 26 Jun 2019 16:32:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="N/a93ebu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726658AbfFZQcJ (ORCPT ); Wed, 26 Jun 2019 12:32:09 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:47658 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726006AbfFZQcI (ORCPT ); Wed, 26 Jun 2019 12:32:08 -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 x5QGU4Wg004218; Wed, 26 Jun 2019 16:30:39 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=Mz7em8B5BcTHywkzCrR8lugIdy2ootcWo4w3RRWBYaM=; b=N/a93ebuSSKM+1UIO0buPOjR9AvCbLsHhw01AwBMp/XW9BUb98JLnzoJbLgwOZFWmGyw hJdpkR7HkvPCAWlWLDnQsdQatbUdssqmn37SwPrTcAyE+/9x/iin4aJ6YtVFtP1GNmmr W4gQLbQG2SBcdOy5QNpDSE2/3fIVqQVrn7mZXub6KhldCj8Zzx/yQQ7a5EH7pzSZXmup IrJvp7zWK9kXgRoeoC8dGqS2tKAzLiR74Ta5S5LQWYLQBZWpbM10fUskgAys8/96vQdr G26RY/thy8CrA4lCa0mPtRoigi2YSG7nQksiKL4VCeGiPZV6yAFAimBMe+B5DQlWGUUd ig== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2130.oracle.com with ESMTP id 2t9brtbf85-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Jun 2019 16:30:39 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x5QGRxdd192423; Wed, 26 Jun 2019 16:28:38 GMT Received: from pps.reinject (localhost [127.0.0.1]) by aserp3020.oracle.com with ESMTP id 2t9p6uvctr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 26 Jun 2019 16:28:38 +0000 Received: from aserp3020.oracle.com (aserp3020.oracle.com [127.0.0.1]) by pps.reinject (8.16.0.27/8.16.0.27) with SMTP id x5QGScxQ193859; Wed, 26 Jun 2019 16:28:38 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3020.oracle.com with ESMTP id 2t9p6uvctj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Jun 2019 16:28:38 +0000 Received: from abhmp0004.oracle.com (abhmp0004.oracle.com [141.146.116.10]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x5QGSZWS032167; Wed, 26 Jun 2019 16:28:35 GMT Received: from localhost (/10.159.137.246) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 26 Jun 2019 09:28:35 -0700 Date: Wed, 26 Jun 2019 09:28:31 -0700 From: "Darrick J. Wong" To: Al Viro Cc: matthew.garrett@nebula.com, yuchao0@huawei.com, tytso@mit.edu, ard.biesheuvel@linaro.org, josef@toxicpanda.com, hch@infradead.org, clm@fb.com, adilger.kernel@dilger.ca, jack@suse.com, dsterba@suse.com, jaegeuk@kernel.org, jk@ozlabs.org, reiserfs-devel@vger.kernel.org, linux-efi@vger.kernel.org, devel@lists.orangefs.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-nilfs@vger.kernel.org, linux-mtd@lists.infradead.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH 5/5] vfs: don't allow writes to swap files Message-ID: <20190626162831.GF5171@magnolia> References: <156151637248.2283603.8458727861336380714.stgit@magnolia> <156151641177.2283603.7806026378321236401.stgit@magnolia> <20190626035151.GA10613@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190626035151.GA10613@ZenIV.linux.org.uk> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9300 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 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-1906260193 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Wed, Jun 26, 2019 at 04:51:51AM +0100, Al Viro wrote: > On Tue, Jun 25, 2019 at 07:33:31PM -0700, Darrick J. Wong wrote: > > --- a/fs/attr.c > > +++ b/fs/attr.c > > @@ -236,6 +236,9 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de > > if (IS_IMMUTABLE(inode)) > > return -EPERM; > > > > + if (IS_SWAPFILE(inode)) > > + return -ETXTBSY; > > + > > if ((ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) && > > IS_APPEND(inode)) > > return -EPERM; > > Er... So why exactly is e.g. chmod(2) forbidden for swapfiles? Or touch(1), > for that matter... Oops, that check is overly broad; I think the only attribute change we need to filter here is ATTR_SIZE.... which we could do unconditionally in inode_newsize_ok. What's the use case for allowing userspace to increase the size of an active swapfile? I don't see any; the kernel has a permanent lease on the file space mapping (at least until swapoff)... > > diff --git a/mm/swapfile.c b/mm/swapfile.c > > index 596ac98051c5..1ca4ee8c2d60 100644 > > --- a/mm/swapfile.c > > +++ b/mm/swapfile.c > > @@ -3165,6 +3165,19 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > > if (error) > > goto bad_swap; > > > > + /* > > + * Flush any pending IO and dirty mappings before we start using this > > + * swap file. > > + */ > > + if (S_ISREG(inode->i_mode)) { > > + inode->i_flags |= S_SWAPFILE; > > + error = inode_drain_writes(inode); > > + if (error) { > > + inode->i_flags &= ~S_SWAPFILE; > > + goto bad_swap; > > + } > > + } > > Why are swap partitions any less worthy of protection? Hmm, yeah, S_SWAPFILE should apply to block devices too. I figured that the mantra of "sane tools will open block devices with O_EXCL" should have sufficed, but there's really no reason to allow that either. --D From mboxrd@z Thu Jan 1 00:00:00 1970 From: Darrick J. Wong Date: Wed, 26 Jun 2019 09:28:31 -0700 Subject: [Ocfs2-devel] [PATCH 5/5] vfs: don't allow writes to swap files In-Reply-To: <20190626035151.GA10613@ZenIV.linux.org.uk> References: <156151637248.2283603.8458727861336380714.stgit@magnolia> <156151641177.2283603.7806026378321236401.stgit@magnolia> <20190626035151.GA10613@ZenIV.linux.org.uk> Message-ID: <20190626162831.GF5171@magnolia> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Al Viro Cc: matthew.garrett@nebula.com, yuchao0@huawei.com, tytso@mit.edu, ard.biesheuvel@linaro.org, josef@toxicpanda.com, hch@infradead.org, clm@fb.com, adilger.kernel@dilger.ca, jack@suse.com, dsterba@suse.com, jaegeuk@kernel.org, jk@ozlabs.org, reiserfs-devel@vger.kernel.org, linux-efi@vger.kernel.org, devel@lists.orangefs.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-nilfs@vger.kernel.org, linux-mtd@lists.infradead.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org On Wed, Jun 26, 2019 at 04:51:51AM +0100, Al Viro wrote: > On Tue, Jun 25, 2019 at 07:33:31PM -0700, Darrick J. Wong wrote: > > --- a/fs/attr.c > > +++ b/fs/attr.c > > @@ -236,6 +236,9 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de > > if (IS_IMMUTABLE(inode)) > > return -EPERM; > > > > + if (IS_SWAPFILE(inode)) > > + return -ETXTBSY; > > + > > if ((ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) && > > IS_APPEND(inode)) > > return -EPERM; > > Er... So why exactly is e.g. chmod(2) forbidden for swapfiles? Or touch(1), > for that matter... Oops, that check is overly broad; I think the only attribute change we need to filter here is ATTR_SIZE.... which we could do unconditionally in inode_newsize_ok. What's the use case for allowing userspace to increase the size of an active swapfile? I don't see any; the kernel has a permanent lease on the file space mapping (at least until swapoff)... > > diff --git a/mm/swapfile.c b/mm/swapfile.c > > index 596ac98051c5..1ca4ee8c2d60 100644 > > --- a/mm/swapfile.c > > +++ b/mm/swapfile.c > > @@ -3165,6 +3165,19 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > > if (error) > > goto bad_swap; > > > > + /* > > + * Flush any pending IO and dirty mappings before we start using this > > + * swap file. > > + */ > > + if (S_ISREG(inode->i_mode)) { > > + inode->i_flags |= S_SWAPFILE; > > + error = inode_drain_writes(inode); > > + if (error) { > > + inode->i_flags &= ~S_SWAPFILE; > > + goto bad_swap; > > + } > > + } > > Why are swap partitions any less worthy of protection? Hmm, yeah, S_SWAPFILE should apply to block devices too. I figured that the mantra of "sane tools will open block devices with O_EXCL" should have sufficed, but there's really no reason to allow that either. --D From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3706C48BD6 for ; Wed, 26 Jun 2019 16:31:58 +0000 (UTC) Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B120820665; Wed, 26 Jun 2019 16:31:58 +0000 (UTC) Authentication-Results: mail.kernel.org; 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Wed, 26 Jun 2019 09:28:35 -0700 Date: Wed, 26 Jun 2019 09:28:31 -0700 From: "Darrick J. Wong" To: Al Viro Message-ID: <20190626162831.GF5171@magnolia> References: <156151637248.2283603.8458727861336380714.stgit@magnolia> <156151641177.2283603.7806026378321236401.stgit@magnolia> <20190626035151.GA10613@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190626035151.GA10613@ZenIV.linux.org.uk> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9300 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 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-1906260193 X-Headers-End: 1hgApv-00B7pa-7U Subject: Re: [f2fs-dev] [PATCH 5/5] vfs: don't allow writes to swap files X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-efi@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org, clm@fb.com, adilger.kernel@dilger.ca, matthew.garrett@nebula.com, linux-nilfs@vger.kernel.org, hch@infradead.org, linux-ext4@vger.kernel.org, devel@lists.orangefs.org, josef@toxicpanda.com, reiserfs-devel@vger.kernel.org, dsterba@suse.com, jaegeuk@kernel.org, tytso@mit.edu, ard.biesheuvel@linaro.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, jk@ozlabs.org, jack@suse.com, linux-fsdevel@vger.kernel.org, linux-mtd@lists.infradead.org, ocfs2-devel@oss.oracle.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Wed, Jun 26, 2019 at 04:51:51AM +0100, Al Viro wrote: > On Tue, Jun 25, 2019 at 07:33:31PM -0700, Darrick J. Wong wrote: > > --- a/fs/attr.c > > +++ b/fs/attr.c > > @@ -236,6 +236,9 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de > > if (IS_IMMUTABLE(inode)) > > return -EPERM; > > > > + if (IS_SWAPFILE(inode)) > > + return -ETXTBSY; > > + > > if ((ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) && > > IS_APPEND(inode)) > > return -EPERM; > > Er... So why exactly is e.g. chmod(2) forbidden for swapfiles? Or touch(1), > for that matter... Oops, that check is overly broad; I think the only attribute change we need to filter here is ATTR_SIZE.... which we could do unconditionally in inode_newsize_ok. What's the use case for allowing userspace to increase the size of an active swapfile? I don't see any; the kernel has a permanent lease on the file space mapping (at least until swapoff)... > > diff --git a/mm/swapfile.c b/mm/swapfile.c > > index 596ac98051c5..1ca4ee8c2d60 100644 > > --- a/mm/swapfile.c > > +++ b/mm/swapfile.c > > @@ -3165,6 +3165,19 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > > if (error) > > goto bad_swap; > > > > + /* > > + * Flush any pending IO and dirty mappings before we start using this > > + * swap file. > > + */ > > + if (S_ISREG(inode->i_mode)) { > > + inode->i_flags |= S_SWAPFILE; > > + error = inode_drain_writes(inode); > > + if (error) { > > + inode->i_flags &= ~S_SWAPFILE; > > + goto bad_swap; > > + } > > + } > > Why are swap partitions any less worthy of protection? Hmm, yeah, S_SWAPFILE should apply to block devices too. I figured that the mantra of "sane tools will open block devices with O_EXCL" should have sufficed, but there's really no reason to allow that either. --D _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C86BBC48BD6 for ; Wed, 26 Jun 2019 16:31:32 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9D0E42133F for ; 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Wed, 26 Jun 2019 16:28:38 +0000 Received: from aserp3020.oracle.com (aserp3020.oracle.com [127.0.0.1]) by pps.reinject (8.16.0.27/8.16.0.27) with SMTP id x5QGScxQ193859; Wed, 26 Jun 2019 16:28:38 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3020.oracle.com with ESMTP id 2t9p6uvctj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Jun 2019 16:28:38 +0000 Received: from abhmp0004.oracle.com (abhmp0004.oracle.com [141.146.116.10]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x5QGSZWS032167; Wed, 26 Jun 2019 16:28:35 GMT Received: from localhost (/10.159.137.246) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 26 Jun 2019 09:28:35 -0700 Date: Wed, 26 Jun 2019 09:28:31 -0700 From: "Darrick J. Wong" To: Al Viro Subject: Re: [PATCH 5/5] vfs: don't allow writes to swap files Message-ID: <20190626162831.GF5171@magnolia> References: <156151637248.2283603.8458727861336380714.stgit@magnolia> <156151641177.2283603.7806026378321236401.stgit@magnolia> <20190626035151.GA10613@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190626035151.GA10613@ZenIV.linux.org.uk> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9300 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 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-1906260193 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190626_093104_752002_8233BEA2 X-CRM114-Status: GOOD ( 17.92 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-efi@vger.kernel.org, linux-btrfs@vger.kernel.org, yuchao0@huawei.com, linux-mm@kvack.org, clm@fb.com, adilger.kernel@dilger.ca, matthew.garrett@nebula.com, linux-nilfs@vger.kernel.org, hch@infradead.org, linux-ext4@vger.kernel.org, devel@lists.orangefs.org, josef@toxicpanda.com, reiserfs-devel@vger.kernel.org, dsterba@suse.com, jaegeuk@kernel.org, tytso@mit.edu, ard.biesheuvel@linaro.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, jk@ozlabs.org, jack@suse.com, linux-fsdevel@vger.kernel.org, linux-mtd@lists.infradead.org, ocfs2-devel@oss.oracle.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Wed, Jun 26, 2019 at 04:51:51AM +0100, Al Viro wrote: > On Tue, Jun 25, 2019 at 07:33:31PM -0700, Darrick J. Wong wrote: > > --- a/fs/attr.c > > +++ b/fs/attr.c > > @@ -236,6 +236,9 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de > > if (IS_IMMUTABLE(inode)) > > return -EPERM; > > > > + if (IS_SWAPFILE(inode)) > > + return -ETXTBSY; > > + > > if ((ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) && > > IS_APPEND(inode)) > > return -EPERM; > > Er... So why exactly is e.g. chmod(2) forbidden for swapfiles? Or touch(1), > for that matter... Oops, that check is overly broad; I think the only attribute change we need to filter here is ATTR_SIZE.... which we could do unconditionally in inode_newsize_ok. What's the use case for allowing userspace to increase the size of an active swapfile? I don't see any; the kernel has a permanent lease on the file space mapping (at least until swapoff)... > > diff --git a/mm/swapfile.c b/mm/swapfile.c > > index 596ac98051c5..1ca4ee8c2d60 100644 > > --- a/mm/swapfile.c > > +++ b/mm/swapfile.c > > @@ -3165,6 +3165,19 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > > if (error) > > goto bad_swap; > > > > + /* > > + * Flush any pending IO and dirty mappings before we start using this > > + * swap file. > > + */ > > + if (S_ISREG(inode->i_mode)) { > > + inode->i_flags |= S_SWAPFILE; > > + error = inode_drain_writes(inode); > > + if (error) { > > + inode->i_flags &= ~S_SWAPFILE; > > + goto bad_swap; > > + } > > + } > > Why are swap partitions any less worthy of protection? Hmm, yeah, S_SWAPFILE should apply to block devices too. I figured that the mantra of "sane tools will open block devices with O_EXCL" should have sufficed, but there's really no reason to allow that either. --D ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/ From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Darrick J. Wong" Subject: Re: [PATCH 5/5] vfs: don't allow writes to swap files Date: Wed, 26 Jun 2019 09:28:31 -0700 Message-ID: <20190626162831.GF5171@magnolia> References: <156151637248.2283603.8458727861336380714.stgit@magnolia> <156151641177.2283603.7806026378321236401.stgit@magnolia> <20190626035151.GA10613@ZenIV.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : message-id : references : mime-version : in-reply-to : cc : subject : list-id : list-unsubscribe : list-archive : list-post : list-help : list-subscribe : content-type : content-transfer-encoding : sender; s=corp-2018-07-02; bh=oYrFpsa7m38VFCZxdd8UBdtHC2a21A24EtIJKYREoCg=; b=jm8jqu9ruZ0MEtEIAH4kN/hgvN31119e8F/bImT0+fLkPBSVa+JeHUB3ar2Yoay3emFd fDg/Bc+rpRBTmobzpLO9zjW0cU7fpU/8F2DCpsoOcq7bWk2dN0+en9t2cizYXNBFITN0 hqW38Kd4AjJi7vv3DgA0rWKShw/86YRobN8LHuC0e9FNAzJLYNAtNfqoPssKkh3Zc/uJ ElAjdCgai0LL2Sh42zqP+adecQ/OlgRFo24KCVUGneTIeenUbY3vgNVtbCZLpJloBOZ/ FtYgL+HauZfd9RKS4wXV/w1Z3keELg9x/8Ky3qkIIzb7cUyhC49/Q76/Yi6/8mSeP864 zA== Content-Disposition: inline In-Reply-To: <20190626035151.GA10613@ZenIV.linux.org.uk> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com To: Al Viro Cc: linux-efi@vger.kernel.org, linux-btrfs@vger.kernel.org, yuchao0@huawei.com, linux-mm@kvack.org, clm@fb.com, adilger.kernel@dilger.ca, matthew.garrett@nebula.com, linux-nilfs@vger.kernel.org, hch@infradead.org, linux-ext4@vger.kernel.org, devel@lists.orangefs.org, josef@toxicpanda.com, reiserfs-devel@vger.kernel.org, dsterba@suse.com, jaegeuk@kernel.org, tytso@mit.edu, ard.biesheuvel@linaro.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, jk@ozlabs.org, jack@suse.com, linux-fsdevel@vger.kernel.org, linux-mtd@lists.infradead.org, ocfs2-devel@oss.oracle.com On Wed, Jun 26, 2019 at 04:51:51AM +0100, Al Viro wrote: > On Tue, Jun 25, 2019 at 07:33:31PM -0700, Darrick J. Wong wrote: > > --- a/fs/attr.c > > +++ b/fs/attr.c > > @@ -236,6 +236,9 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de > > if (IS_IMMUTABLE(inode)) > > return -EPERM; > > > > + if (IS_SWAPFILE(inode)) > > + return -ETXTBSY; > > + > > if ((ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) && > > IS_APPEND(inode)) > > return -EPERM; > > Er... So why exactly is e.g. chmod(2) forbidden for swapfiles? Or touch(1), > for that matter... Oops, that check is overly broad; I think the only attribute change we need to filter here is ATTR_SIZE.... which we could do unconditionally in inode_newsize_ok. What's the use case for allowing userspace to increase the size of an active swapfile? I don't see any; the kernel has a permanent lease on the file space mapping (at least until swapoff)... > > diff --git a/mm/swapfile.c b/mm/swapfile.c > > index 596ac98051c5..1ca4ee8c2d60 100644 > > --- a/mm/swapfile.c > > +++ b/mm/swapfile.c > > @@ -3165,6 +3165,19 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > > if (error) > > goto bad_swap; > > > > + /* > > + * Flush any pending IO and dirty mappings before we start using this > > + * swap file. > > + */ > > + if (S_ISREG(inode->i_mode)) { > > + inode->i_flags |= S_SWAPFILE; > > + error = inode_drain_writes(inode); > > + if (error) { > > + inode->i_flags &= ~S_SWAPFILE; > > + goto bad_swap; > > + } > > + } > > Why are swap partitions any less worthy of protection? Hmm, yeah, S_SWAPFILE should apply to block devices too. I figured that the mantra of "sane tools will open block devices with O_EXCL" should have sufficed, but there's really no reason to allow that either. --D