On 10.11.21 20:36, Simon Glass wrote: > Hi Jan, > > On Wed, 10 Nov 2021 at 09:49, Jan Kiszka <jan.kis...@siemens.com> wrote: >> >> 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? > > Using map files for what? Do you mean passing it to Binman in lieu of > an in-image fdtmap? If so, they are not equivalent. The map is just a > simple text output of offsets and sizes. The fdtmap contains the full > image description.
Too bad. I was looking for a way to avoid having to add fdtmap to an image when all information is already on the build host - and should actually only remain there. Embedding fdtmap into the image solely for build/post-process purposes looks like overkill to me. > >> >>> >>>> >>>> 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. > > Well, at present the information is there but Binman does not fully > parse the mkimage subnodes. E.g. it doesn't look to see what things > are signed/hashed. It just runs mkimage. If we want to output the hash > for signing, we would need to implement that somewhere. Binman could > do this after the image is build, i.e. look at the various signature > nodes, hash the appropriate data and write out an 'instructions' file > in a suitable format. Yep, that would be nice. Or would mkimage have more of the needed logic already on board and would better be extended to write them out? Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux