Messages in this thread | | | Date | Thu, 8 Jul 2010 08:46:48 -0700 | From | Greg KH <> | Subject | Re: BUG: Securityfs and bind mounts (2.6.34) |
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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.
thanks,
greg k-h
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