Re: [patch 1/4] Add routine for generating an ID for kernel pointer

[bastien ROUCARIES]

Le Saturday 31 December 2011 08:51:02, Cyrill Gorcunov a écrit :
> On Fri, Dec 30, 2011 at 06:51:37PM -0500, KOSAKI Motohiro wrote:
> ...
> 
> > >Guys, this become more and more complex, finally I fear someone
> > >propose to do ideal hashing run-time ;) Maybe we can step back and
> > >live with root-only and plain pointers here? I'm not sure who else
> > >might need such facility except us, and if once there will be a
> > >candidate -- we could take a look on hashing again and provide safe
> > >hashes there. No?
> > 
> > But recently kernel security fashion are, we don't expose a kernel
> > pointer at all even though the file is root only. I'm not sure how
> > much effective such fashion. but you seems run opposite way.
> > 
> > I doubt user land can implement good comparison way. Why you gave up
> > Andrew's sys_are_these_files_the_same() idea?

By memory, it seems that fuse expose kernel pointer encrypting it with tea. Tea is simple and quick you should get a glimpse at 
it.

> Because of speed, as Pavel mentioned
> 
>  | With this the complexity of determining sharing for N files scattered
>  | across several tasks would be N^2, since we'll have to compare each
>  | file to each file.
>  | 
>  | On the other hand having just N IDs at hands would allow us to use more
>  | efficient algorithms resulting in e.g. N*log(N) complexity.



> 	Cyrill
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/