On Fri, 31 May 2019 at 19:25, Ilias Apalodimas <ilias.apalodi...@linaro.org> wrote: > > Hi Grant, > > I see two ways to handle this that fits with the Secure Boot > > authentication path: > > > > Option 1: Leave it to the OS loader > > We could simply say that if the OS wants to replace the DTB, then it > > should take care of authentication itself within the OS loader (possibly > > the in-kernel UEFI stub) and install a replacement DTB in the > > configuration table before calling exit boot services. In this scenario, > > U-Boot doesn't authenticate the DTB at all. > > > > In fact, Option 1 is pretty close to what is required for the initrd. > > > > I wonder if it is possible to wrap the DTB with a PE/COFF so that the os > > loader can use load_image to authenticate and retrieve the data without > > actually executing the image. That would allow for the DTB & initrd to > > be authenticated in the same way as the kernel. > I asked around on this prior to the email, but i think it boils down to > "UEFI is intended to authenticate bootable images for the platform", so i > doubt > this will be allowed. >
The point I raised when we discussed this is that UEFI is an interface between the firmware and the OS, and it is up to the firmware to *provide* the DT not the other way around. Whether the firmware reuses some of the existing machinery if it chooses to load the DT it provides from an arbitrary file on the file system is an implementation detail, and shouldn't be part of how we design the interface. The more we standardize this and the more we make it similar to how the OS loader is authenticated, the more likely it becomes that it will be relied upon for DTs that are bundled with the OS, which is a practice we are trying very hard to move away from. _______________________________________________ boot-architecture mailing list boot-architecture@lists.linaro.org https://lists.linaro.org/mailman/listinfo/boot-architecture
