[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Mon, 14 Mar 2011 14:28:59 +0100
From: Ludwig Nussel <ludwig.nussel@...e.de>
To: oss-security@...ts.openwall.com
Subject: Re: Untrusted fs and invalid filenames
Stephan Mueller wrote:
> Am Samstag, 12. März 2011, um 18:03:45 schrieb Vasiliy Kulikov:
> > What I suggest is something like "-o untrusted" option to mount. This
> > would mean that the system considers the input from such fs as a malicious
> > input. Such mounted fs would try to consider the data on disk as
> > untrusted and to be as robust as possible, e.g. check against
> > "/"-filenames, against corrupted fs structures, etc. I'd be happy to
> > hear opinions about the usefulness of this feature.
>
> I completely second your concerns.
>
> However, how do you propose to implement that "untrusted" option? The core
> problem IMHO is that the physical layout and structure in a file system is
> assumed to be correct in general by the kernel. The physical file system
> implementations (including any depending code, like the LSMs for interpreting
> XATTRs) have some checks for an input validation. But I highly doubt that all
> checks necessary for an untrusted file system layout are implemented - to have
> all such checks would cause some speed penalties nobody wants to carry.
For the hot plugged USB drive case speed of the file system
shouldn't be much of a concern. I wonder whether it would be
possible to create a wrapper API that allow to compile kernel fs
modules as user space programs for use with e.g. fuse.
cu
Ludwig
--
(o_ Ludwig Nussel
//\
V_/_ http://www.suse.de/
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nuernberg)
Powered by blists - more mailing lists
Please check out the
Open Source Software Security Wiki, which is counterpart to this
mailing list.
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
