From: Florian Weimer <fweimer@redhat.com>
To: Matthew Wilcox <matthew.r.wilcox@intel.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org, willy@linux.intel.com
Subject: Re: [PATCH v6 00/22] Support ext4 on NV-DIMMs
Date: Thu, 27 Feb 2014 15:01:03 +0100 [thread overview]
Message-ID: <530F451F.9020107@redhat.com> (raw)
In-Reply-To: <1393337918-28265-1-git-send-email-matthew.r.wilcox@intel.com>
On 02/25/2014 03:18 PM, Matthew Wilcox wrote:
> One of the primary uses for NV-DIMMs is to expose them as a block device
> and use a filesystem to store files on the NV-DIMM. While that works,
> it currently wastes memory and CPU time buffering the files in the page
> cache. We have support in ext2 for bypassing the page cache, but it
> has some races which are unfixable in the current design. This series
> of patches rewrite the underlying support, and add support for direct
> access to ext4.
I'm wondering if there is a potential security issue lurking here.
Some distributions use udisks2 to grant permission to local console
users to create new loop devices from files. File systems on these
block devices are then mounted. This is a replacement for several file
systems implemented in user space, and for the users, this is a good
thing because the in-kernel implementations are generally of higher quality.
What happens if we have DAX support in the entire stack, and an
enterprising user mounts a file system? Will she be able to fuzz the
file system or binfmt loaders concurrently, changing the bits while they
are being read?
Currently, it appears that the loop device duplicates pages in the page
cache, so this does not seem to be possible, but DAX support might
change this.
--
Florian Weimer / Red Hat Product Security Team
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next prev parent reply other threads:[~2014-02-27 14:01 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-25 14:18 [PATCH v6 00/22] Support ext4 on NV-DIMMs Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 01/22] Fix XIP fault vs truncate race Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 02/22] Allow page fault handlers to perform the COW Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 03/22] axonram: Fix bug in direct_access Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 04/22] Change direct_access calling convention Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 05/22] Introduce IS_DAX(inode) Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 06/22] Replace XIP read and write with DAX I/O Matthew Wilcox
2014-03-11 0:32 ` Toshi Kani
2014-03-11 12:53 ` Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 07/22] Replace the XIP page fault handler with the DAX page fault handler Matthew Wilcox
2014-02-28 17:49 ` Toshi Kani
2014-02-28 20:20 ` Matthew Wilcox
2014-02-28 22:18 ` Toshi Kani
2014-03-02 23:30 ` Dave Chinner
2014-03-03 23:07 ` Ross Zwisler
2014-03-04 0:56 ` Dave Chinner
2014-03-20 19:38 ` Matthew Wilcox
2014-03-20 23:55 ` Dave Chinner
2014-02-25 14:18 ` [PATCH v6 08/22] Replace xip_truncate_page with dax_truncate_page Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 09/22] Remove mm/filemap_xip.c Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 10/22] Remove get_xip_mem Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 11/22] Replace ext2_clear_xip_target with dax_clear_blocks Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 12/22] ext2: Remove ext2_xip_verify_sb() Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 13/22] ext2: Remove ext2_use_xip Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 14/22] ext2: Remove xip.c and xip.h Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 15/22] Remove CONFIG_EXT2_FS_XIP and rename CONFIG_FS_XIP to CONFIG_FS_DAX Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 16/22] ext2: Remove ext2_aops_xip Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 17/22] Get rid of most mentions of XIP in ext2 Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 18/22] xip: Add xip_zero_page_range Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 19/22] ext4: Make ext4_block_zero_page_range static Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 20/22] ext4: Add DAX functionality Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 21/22] ext4: Fix typos Matthew Wilcox
2014-02-25 14:18 ` [PATCH v6 22/22] dax: Add reporting of major faults Matthew Wilcox
2014-02-26 15:07 ` [PATCH v6 23/22] Bugfixes Matthew Wilcox
2014-02-27 14:01 ` Florian Weimer [this message]
2014-02-27 16:29 ` [PATCH v6 00/22] Support ext4 on NV-DIMMs Matthew Wilcox
2014-02-27 16:36 ` Florian Weimer
2014-03-02 8:22 ` Pavel Machek
[not found] ` <CF4DEE22.25C8F%matthew.r.wilcox@intel.com>
2014-03-18 18:45 ` [PATCH v6 20/22] ext4: Add DAX functionality Ross Zwisler
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