On September 18, 2022 8:52 PM, Ard Biesheuvel wrote: > Hello Min Xu, > > On Sat, 17 Sept 2022 at 04:53, Xu, Min M <min.m...@intel.com> wrote: > > > > Hi, Ard > > > > I am checking the measurement behavior when loading the kernel via the > QEMU -kernel option. I find it is implemented by below 2 driver/lib: > > > > - OvmfPkg/QemuKernelLoaderFsDxe > > > > This is a separate DXE driver that exposes the virtual SimpleFileSystem > implementation that carries the kernel and initrd passed via the QEMU > command line. > > > > - OvmfPkg/Library/X86QemuLoadImageLib > > > > This is the library that consumes above driver and call > LoadImage/StartImage so that the kernel image gets authenticated and/or > measured. > > > > See https://edk2.groups.io/g/devel/message/55381 > > > > > > > > I have some questions about the implementation need your help. > > > > 2. Kernel image is authenticated and/or measured in LoadImage. I am > wondering if “command line” is measured as well? “Command line” can be > treated as an external input and in my opinion it should be measured too. > > > > 3. The same question to initrd. Is it measured? > > > > The initrd is measured by the EFI stub in Linux, and we are currently adding > measurement of the load options to that as well: > https://lore.kernel.org/all/20220916081441.1993492-2- > ilias.apalodi...@linaro.org/ > > The initrd is Linux specific in any case, so there, the Linux OS loader is a > natural place to take care of this. The load options are being added because > of the oversight in the TCG spec, which only covers load options if they are > part of a Boot#### option, but between > LoadImage() and StartImage, you can pass any load options you want via the > loaded image protocol, so it needs to be measured as well. > Thanks Ard for the explanation. I was told that in grub boot cmd-line/initrd will be measured as well. So my question is that will they be measured twice? One in grub.efi, the other in efi-stub?
My understanding is that the loader should take the responsibility to do the measurement. For grub boot, grub.efi is the loader so it measures kernel-image/cmd-line/initrd. For direct boot, TryRunningQemuKernel() now measures kernel image (in CoreLoadImage). Shall it also measure cmd-line/initrd in the same time? Thanks Min -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#93922): https://edk2.groups.io/g/devel/message/93922 Mute This Topic: https://groups.io/mt/93737108/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
