Re: [PATCH v6 00/22] Support ext4 on NV-DIMMs

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux