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79d3219d4e
One of the advantages of using what basically amounts to a callback interface into the bootloader for loading the initrd is that it provides a natural place for the bootloader or firmware to measure the initrd contents while they are being passed to the kernel. Unfortunately, this is not a guarantee that the initrd will in fact be loaded and its /init invoked by the kernel, since the command line may contain the 'noinitrd' option, in which case the initrd is ignored, but this will not be reflected in the PCR that covers the initrd measurement. This could be addressed by measuring the command line as well, and including that PCR in the attestation policy, but this locks down the command line completely, which may be too restrictive. So let's take the noinitrd argument into account in the stub, too. This forces any PCR that covers the initrd to assume a different value when noinitrd is passed, allowing an attestation policy to disregard the command line if there is no need to take its measurement into account for other reasons. As Peter points out, this would still require the agent that takes the measurements to measure a separator event into the PCR in question at ExitBootServices() time, to prevent replay attacks using the known measurement from the TPM log. Cc: Peter Jones <pjones@redhat.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> |
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| .. | ||
| arm32-stub.c | ||
| arm64-stub.c | ||
| arm-stub.c | ||
| efi-stub-helper.c | ||
| efistub.h | ||
| fdt.c | ||
| file.c | ||
| gop.c | ||
| hidden.h | ||
| Makefile | ||
| mem.c | ||
| pci.c | ||
| random.c | ||
| randomalloc.c | ||
| secureboot.c | ||
| skip_spaces.c | ||
| string.c | ||
| tpm.c | ||
| x86-stub.c | ||