Re: [GIT PULL] Asymmetric keys and module signing

From: Rusty Russell
Date: Wed Sep 26 2012 - 22:05:45 EST


David Howells <dhowells@xxxxxxxxxx> writes:

> Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:
>
>> We do a very simple search for a particular string appended to the module
>> (which is cache-hot and about to be SHA'd anyway). There's both a config
>> option and a boot parameter which control whether we accept (and taint) or
>> fail with unsigned modules.
>
> I've adjusted your patch description to this:
>
> We do a very simple search for a particular string appended to the module
> (which is cache-hot and about to be SHA'd anyway). There's both a config
> option and a boot parameter which control whether we accept or fail with
> unsigned modules and modules that are signed with an unknown key.
>
> If module signing is enabled, the kernel will be tainted if a module is
> accepted that is unsigned or has a signature for which we don't have the
> key.
>
> I think it's worth mentioning the policy for unknown keys and worth making
> clear under what circumstances we mean the kernel to be tainted.

Great! I checked your Kconfig help, too, which is states it clearly:

config MODULE_SIG_FORCE
bool "Require modules to be validly signed"
depends on MODULE_SIG
help
Reject unsigned modules or signed modules for which we don't have a
key. Without this, such modules will simply taint the kernel.


Which is really nice, since the kernel Kconfig help messages tend to
suck.

Thanks,
Rusty.
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