AKASHI Takahiro <takahiro.akashi at linaro.org> writes: > Device tree blob must be passed to a second kernel on DTB-capable > archs, like powerpc and arm64, but the current kernel interface > lacks this support. > > This patch extends kexec_file_load system call by adding an extra > argument to this syscall so that an arbitrary number of file descriptors > can be handed out from user space to the kernel. > > See the background [1]. > > Please note that the new interface looks quite similar to the current > system call, but that it won't always mean that it provides the "binary > compatibility." > > [1] http://lists.infradead.org/pipermail/kexec/2016-June/016276.html So this design is wrong. The kernel already has the device tree blob, you should not be extracting it from the kernel munging it, and then reinserting it in the kernel if you want signatures and everything to pass. What x86 does is pass it's equivalent of the device tree blob from one kernel to another directly and behind the scenes. It does not go through userspace for this. Until a persuasive case can be made for going around the kernel and probably adding a feature (like code execution) that can be used to defeat the signature scheme I am going to nack this. Nacked-by: "Eric W. Biederman" <ebiederm at xmission.com> I am happy to see support for other architectures, but for the sake of not moving some code in the kernel let's not build an attackable infrastructure. Eric