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SubjectRe: [PATCH] Adding Documentation/module-signing.txt file
On 10/24/2013 07:08:33 PM, Josh Boyer wrote:
> On Thu, Oct 24, 2013 at 6:35 PM, James Solner
> <solner@alcatel-lucent.com> wrote:
> > This patch adds the Documentation/module-signing.txt file that is
> > missing. There is a link to Documentation/module-signing.txt file
> > in init/Kconfig that references this file.
> >
> > Signed-off-by: James Solner <solner@alcatel-lucent.com>
>
> Nak. Please see below.
>
> > ---
> > Documentation/module-signing.txt | 182
> +++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 182 insertions(+)
> > create mode 100644 Documentation/module-signing.txt
> >
> > diff --git a/Documentation/module-signing.txt
> b/Documentation/module-signing.txt
> > new file mode 100644
> > index 0000000..b21e1f1
> > --- /dev/null
> > +++ b/Documentation/module-signing.txt
> > @@ -0,0 +1,182 @@
> > + ==============================
> > + KERNEL MODULE SIGNING FACILITY
> > + ==============================
> > +
> > +The module signing facility applies cryptographic signature
> checking to modules
> > +on module load, checking the signature against a ring of public
> keys compiled
> > +into the kernel. GPG is used to do the cryptographic work and
> determines the
> > +format of the signature and key data. The facility uses GPG&#39;s
> MPI library to
> > +handle the huge numbers involved.
> > +
> > +The signature checker in the kernel is capable of handling
> multiple keys of
> > +either DSA or RSA type, and can support any of MD5, RIPE-MD-160,
> SHA-1,
> > +SHA-224, SHA-256, SHA-384 and SHA-512 hashes - PROVIDED(!) the
> requisite
> > +algorithms are compiled into the kernel.
> > +
> > +(!) NOTE: Modules may only be verified initially with algorithms
> compiled into
> > +the kernel. Further algorithm modules may be loaded and used -
> but these must
> > +first pass a verification step using already loaded/compiled-in
> algorithms.
> > +
> > +
> > +=====================
> > +SUPPLYING PUBLIC KEYS
> > +=====================
> > +
> > +A set of public keys must be supplied at kernel image build time.
> This is done
> > +by taking a GPG public key file and placing it in the base of the
> kernel
> > +directory in a file called modsign.pub.
> > +
> > +For example, a throwaway key could be generated automatically by
> something like
> > +the following:
> > +
> > + cat &gt;genkey &lt;&lt;EOF
> > + %pubring modsign.pub
> > + %secring modsign.sec
> > + Key-Type: RSA
> > + Key-Length: 4096
> > + Name-Real: A. N. Other
> > + Name-Comment: Kernel Module GPG key
> > + %commit
> > + EOF
> > + gpg --homedir . --batch --gen-key genkey
> > +
> > +The above generates fresh keys using /dev/random. If there&#39;s
> insufficient data
> > +in /dev/random, more can be provided using the rngd program if
> there&#39;s a
> > +hardware random number generator available.
> > +
> > +Note that no GPG password is used in the above scriptlet.
>
> This is inaccurate and doesn't match how module signing is done today.
> The document you have here is a weird mix of the old RHEL style GPG
> signing and the current appended-signature x509 certificate signing.
>
> It needs to be updated to match the fact that x509 keys and signatures
> are used now.
>
> josh

What's the current status of this? I'm collating my Documentation patch
stack to submit upstream, and this is the most recent message on this
one?

(Googling for Documentation/module-signing.txt brings up dhowells tree
on googlesource.com, so presumably something could be fished out of
that, but maybe it's going upstream via Rusty's tree, or...?)

*shrug* Just trying to keep tabs...

Rob

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