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    SubjectRe: BUG: Securityfs and bind mounts (2.6.34)
    On Thu, Jul 08, 2010 at 04:32:42PM +0100, Tvrtko Ursulin wrote:
    > On Thursday 08 Jul 2010 16:20:59 Greg KH wrote:
    > > > :) Well I do not know, but, it kind of smelled like a bug in the
    > > > : vfs/mount
    > > >
    > > > handling/securityfs area so I thought to let experts know. I _think_ I
    > > > did nothing that much wrong. Just used the exposed API
    > > > (securityfs_remove) and some bind mount shuffling from userspace.
    > >
    > > securitfs just uses libfs underneath it, and really doesn't have any
    > > bindings for module ownerships, so I wouldn't recommend doing what you
    > > just did.
    > Just do double check what you are saying, securityfs is not safe for use from
    > modules? If so I would then recommend removing the exports otherwise it is an
    > invitation to shoot yourself into the foot.

    Hm, did you properly set the module owner of the file_operations that
    you passed to securityfs? That should protect if you have an open file,
    but I doubt anyone thought you would do crazy things like bind mounts on
    top of a ramfs and then think it was safe to unload a lower module :)

    > Also, in-three TPM driver can be built as a module so how does that
    > work?

    You have to be root to unload modules, and if you are that, you can do
    worse things than this.


    greg k-h

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