On 10.11.21 17:31, Simon Glass wrote: > Hi Jan, > > On Wed, 10 Nov 2021 at 00:20, Jan Kiszka <jan.kis...@siemens.com> wrote: >> >> On 10.11.21 07:55, Jan Kiszka wrote: >>> On 10.11.21 01:58, Simon Glass wrote: >>>> Hi, >>>> >>>> On Tue, 9 Nov 2021 at 02:17, Jan Kiszka <jan.kis...@siemens.com> wrote: >>>>> >>>>> On 08.11.21 16:28, Roman Kopytin wrote: >>>>>> In order to reduce the coupling between building the kernel and >>>>>> U-Boot, I'd like a tool that can add a public key to U-Boot's dtb >>>>>> without simultaneously signing a FIT image. That tool doesn't seem to >>>>>> exist, so I stole the necessary pieces from mkimage et al and put it >>>>>> in a single .c file. >>>>>> >>>>>> I'm still working on the details of my proposed "require just k out >>>>>> these n required keys" and how it should be implemented, but it will >>>>>> probably involve teaching this tool a bunch of new options. These >>>>>> patches are not necessarily ready for inclusion (unless someone else >>>>>> finds fdt_add_pubkey useful as is), but I thought I might as well send >>>>>> it out for early comments. >>>>> >>>>> I'd also like to see the usage of this hooked into the build process. >>>>> >>>>> And to my understanding of [1], that approach will provide a feature >>>>> that permits hooking with the build but would expect the key as dtsi >>>>> fragment. Can we consolidate the approaches? >>>>> >>>>> My current vision of a user interface would be a Kconfig option that >>>>> takes a list of key files to be injected. Maybe make that three lists, >>>>> one for "required=image", one for "required=conf", and one for optional >>>>> keys (if that has a use case in practice, no idea). >>>> >>>> Also please take a look at binman which is designed to handle create >>>> (or later updating from Yocto) the devicetree or firmware image. >>>> >>> >>> Yes, binman is another problem area, but not for the public key >>> injection, rather for permitting to sign fit images that are described >>> for binman (rather than for mkimage). I'm currently back to dd for >>> signing the U-Boot container in >>> arch/arm/dts/k3-am65-iot2050-boot-image.dtsi, or I would have to split >>> that FIT image description from that file - both not optimal. > > Well I don't think binman supports that at present, or at least I'm > not sure what it would do. We don't have a test case for it. If you > have an idea for how it should work, please send some ideas and I can > look at it. > >> >> OK, this can already be optimized with "binman replace" - once I >> understood where fdtmap can go and where not. Why no support for using >> map files? > > The fdtmap provides enough information to extract anything from the > image and regenerate/replace things. > > What is a map file?
*.map, e.g. image.map? Also generated by many binmap <cmd> -m? > >> >> Jan >> >>> >>> And another area: Trust centers that perform the signing (and only that) >>> usually do not support random formats and workflows but just few common >>> ones, e.g. x509. It would be nice to have a way to route out the payload >>> (hashes etc.) that mkimage would sign, ideally into a standard signing >>> request, and permit to inject the resulting signature at the right >>> places into the FIT image. > > Well that needs to be provided somewhere. It should be fairly easy to > get Binman to do this, so long as the image description has info about > what is being signed. I would assume that it has to have that information, already to use mkimage on it or its parts. > >>> >>> But one after the other. > > Possibly, but sometimes it is best to design things up-front. > True as well. Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux
