Re: [RFC] module: signature infrastructure

From: Kasatkin, Dmitry
Date: Tue Sep 04 2012 - 19:17:26 EST


On Wed, Sep 5, 2012 at 1:51 AM, David Howells <dhowells@xxxxxxxxxx> wrote:
> Lucas De Marchi <lucas.de.marchi@xxxxxxxxx> wrote:
>
>> Or let the magic string as the last thing in the module and store the
>> signature length, too. In this case no scanning is needed
>
> Indeed. This is the better way.
>
> The main problem is rendering the length from a shell script. It's trivial to
> do as ASCII (there's a printf program), but a pain to render to binary. I'm
> sure it can be done with perl or python without the need to compile anything.
>
> David

That is very easy to do from script as well.
See script in my tree.

http://git.kernel.org/?p=linux/kernel/git/kasatkin/linux-digsig.git;a=blob;f=scripts/modsig.sh;h=4e997c3996d71d8e1afeb3a7afe23b3f303b9f63;hb=59f1d5352969166f2f32f84e07e20dd1b30a890f

110 # add signature length - big endian
111 dec2hex $(stat --printf %s $sigfile) 4 | hex2bin $sigfile
112 echo -n "This Is A Crypto Signed Module" >>$sigfile

well. I have couple of small functions in the script. dec2hex and hex2bin

- Dmitry
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