Re: [PATCH 1/4] module: add syscall to load module from fd

[H. Peter Anvin]

On 10/18/2012 07:23 PM, Rusty Russell wrote:
> "H. Peter Anvin" <hpa@xxxxxxxxx> writes:
> > Given that, I have to say I now seriously question the value of
> > finit_module().  The kernel can trivially discover if the pointed-to
> > memory area is a MAP_SHARED mmap() of a file descriptor and if so which
> > file descriptor... why can't we handle this behind the scenes?
>
> It is a bit more indirect, but also in practice it's a bit trickier than
> that.  We need to ensure the memory doesn't change underneath us and
> stays attached to that fd.  I can easily see that code slipping and
> ending in an exploit.
>
> But that may be my irrational fear of the mm :)

You have to do the same thing with a file/file descriptor, I would think.

However, I keep wondering about the use case for this, as opposed to 
signatures.

	-hpa


--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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