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

From: H. Peter Anvin
Date: Thu Oct 18 2012 - 22:55:19 EST

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.


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

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