WIP: Signing TI x509 certificates using binman

[Simon Glass]

Hi Neha,

On Sat, 1 Apr 2023 at 00:14, Neha Malcom Francis <n-francis at ti.com> wrote:
>
> Hi Simon
>
> On 31/03/23 02:01, Simon Glass wrote:
> > Hi Neha,
> >
> > On Fri, 24 Mar 2023 at 22:28, Neha Malcom Francis <n-francis at ti.com> wrote:
> >>
> >> Hi Simon,
> >>
> >> Before I roll out the entire series that works for packaging K3
> >> bootloader images, wanted to get some reviews and comments regarding the
> >> implementation of the signing etype [1] . I believe I've taken into
> >> consideration what we've discussed earlier [2].
> >>
> >> Let me know your thoughts. The tree is also WIP, and was mainly designed
> >> for testing the signing etype on two of the devices. I will add the
> >> remaining and refine the series based on the next comments.
> >
> > Yes this looks reasonable to me. For the openssl method, can you
> > create a new 'real' method and put the cert stuff in there instead of
> > using a 'custom' one? It seems to have a lot in common with what is
> > there. We should really have an internal cert-generator method in that
> > class, with other functions in that class doing appropriate things. I
> > am looking for code reuse here, as well as clear indication of what
> > the cert is for or does.
>
> So you're suggesting to include the config creation within the openssl
> btool, am I right? For example methods to generate a config, add section
> to a config, add extension to a section of a config... etc? I can take a
> look at implementing this if this is what you have suggested.

I am more thinking that your use case could be a new method in that
file, with arguments that suit your case, but with common code to
create a cert of the correct type. That means pulling out the existing
cert creation into a new (internal) function in that btool that does
both types of cert. For the CN args I think a dict would be suitable
to pass in the settings.

I'm trying to avoid people passing in a cert every time, since that is
going to create a lot of code duplication and it will be hard to take
advantage of common algos.

>
> If most of the cert is the same, you could
> > pass a dict for the CN stuff, perhaps?
> >
> > What is the taml for? It is hard to tell, from the example provided.
> Did you mean YAML? If so in the patch I linked, I don't think I had a
> example for that. Could you point out what exactly you're asking about?

Well I am wondering why it is in the code...is there a yaml file that
you need to ingest and process? What is it for?

...actually I see the yaml files in your tree mentioned below. Does
this come out of some other tool?

>
> >
> > Do you have a .dts which shows the full image for a board? I think the
> > cert stuff looks right, but it's a bit hard to tell.
>
> Yes, in the same github link I have the whole tree [3] that contains
> DTBs for couple of the devices [4] and [5], please have a look and let
> me know (I might force push a few changes in the next couple of days, so
> better to look from the tree)

OK I see. Yes it looks pretty good to me.

>
> >
> > When sending the patches please do do follow the function-commenting
> > style and make sure that it is clear what each arg means. E.g. I saw a
> > hash integer which I assume is used to pass 256 or 384 or 512 for sha
> > hashing. It should indicate the possible values / meaning in the arg.
> > In fact, in that case, it might be better to pass a string like
> > 'sha256'.
>
> Yes, you're right. Will address that when sending the patch series
> completely.

OK

>
> >
> > Anyway, apart from my questions it seems good.
> >
> > Regards,
> > Simon
> >
> >>
> >> [1]
> >> https://github.com/nehamalcom/u-boot/commit/ea7413ed5864340bd6f01e704e8bdcc073a7896b#diff-efb03d61a324724c4f86bf42b45c4e4e614cab18e1b3184f63721d62280a11b5
> >>
> >> [2]
> >> https://patchwork.ozlabs.org/project/uboot/patch/20230224120340.587786-1-n-francis@ti.com/
> >>
> >> --
> >> Thanking You
> >> Neha Malcom Francis
>
> [3] https://github.com/nehamalcom/u-boot/commits/ti-secure-functionality
> [4]
> https://github.com/nehamalcom/u-boot/commit/dda1f9caf436df59c576466f35262df90aa1c0af
>

Regards,
Simon