[v2,0/2] vfs: make active swap files unwritable

Message ID	156174691124.1557844.14293659081769020256.stgit@magnolia (mailing list archive)
Headers	show Return-Path: <owner-linux-mm@kvack.org> Received-SPF: pass (google.com: domain of darrick.wong@oracle.com designates 156.151.31.86 as permitted sender) client-ip=156.151.31.86; Subject: [PATCH v2 0/2] vfs: make active swap files unwritable From: "Darrick J. Wong" <darrick.wong@oracle.com> To: hch@infradead.org, akpm@linux-foundation.org, tytso@mit.edu, viro@zeniv.linux.org.uk, darrick.wong@oracle.com Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Date: Fri, 28 Jun 2019 11:35:11 -0700 Message-ID: <156174691124.1557844.14293659081769020256.stgit@magnolia> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	vfs: make active swap files unwritable \| expand [v2,0/2] vfs: make active swap files unwritable [1/2] mm: set S_SWAPFILE on blockdev swap devices [2/2] vfs: don't allow writes to swap files

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Subject: [PATCH v2 0/2] vfs: make active swap files unwritable
From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: hch@infradead.org, akpm@linux-foundation.org, tytso@mit.edu,
        viro@zeniv.linux.org.uk, darrick.wong@oracle.com
Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Date: Fri, 28 Jun 2019 11:35:11 -0700
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vfs: make active swap files unwritable | expand

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Darrick J. Wong June 28, 2019, 6:35 p.m. UTC

Hi all,

I discovered that it's possible for userspace to write to active swap
files and swap devices.  While activated, the kernel effectively holds
an irrevocable (except by swapoff) longterm lease on the storage
associated with the swap device, so we need to shut down this vector for
memory corruption of userspace programs.

If you're going to start using this mess, you probably ought to just
pull from my git trees, which are linked below.

This has been lightly tested with fstests.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=immutable-swapfiles

fstests git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfstests-dev.git/log/?h=immutable-swapfiles