[...]
+UEFI requirements +~~~~~~~~~~~~~~~~~ +* A hardware TPM 2.0 supported by the U-Boot drivers
by an enabled U-Boot driver.
+* CONFIG_EFI_TCG2_PROTOCOL=y +* CONFIG_EFI_TCG2_PROTOCOL_EVENTLOG_SIZE=y +* optional CONFIG_EFI_TCG2_PROTOCOL_MEASURE_DTB=y will measure the loaded DTB in PCR 0
Why does this setting not default to yes?
Should EFI_TCG2_PROTOCOL_MEASURE_DTB depend on !GENERATE_ACPI_TABLE as we won't load the device-tree in this case?
I can't find any reference to device-trees in `TCG PC Client Platform Firmware Profile Specification`.
It's not and I've already pointed this out to Arm. We followed what ACPI does there and used "DTB DATA" instead of "ACPI DATA" as the event string.
Where is PCR 0 for the device-tree specified?
As I said DT is missing from the spec but look below
I read:
"In general, the platform firmware measures into PCR[1] the configuration data that is associated with the code that measured into PCR[0]".
This looks like PCR 1 should be the target for the device-tree.
There is a description for ACPI in 3.3.4.1 PCR[0] – SRTM, POST BIOS, and Embedded Drivers and they explicitly mention ACPI in there. There's no mention of ACPI in 3.3.4.2 PCR[1] – Host Platform Configuration.
However ..... In Figure 6 PCR Mapping of UEFI Components ACPI is shown in PCR1 ..... I am not sure if we should use PCR0 or 1, if anyone has a strong opinion we can easily change the measured PCR.
Do we already measure ACPI and SMBIOS tables into PCR1 as required by the specification.
We do measure SMBIOS in PCR1. I don't think we do anything for ACPI.
+bootm
Measured legacy boot with bootm command
Please, consider in your description that the bootm command may be used to load a FIT image with an EFI binary.
I am not entirely sure how this works, someone who has used that needs to update it. What happens in that case? Does bootm end up calling bootefi ? That means we are measuring things twice?
+----- By default, U-Boot will measure the operating system (linux) image, the initrd image, and the "bootargs" environment variable. By enabling CONFIG_MEASURE_DEVICETREE, U-Boot will also measure the devicetree image. @@ -15,8 +35,8 @@ The operating system typically would verify that the hashes found in the TPM PCRs match the contents of the event log. This can further be checked against the hash results of previous boots.
-Requirements
+bootm requirements
This is already a sub-section of bootm. No need to repeat it.
+~~~~~~~~~~~~~~~~~~
- A hardware TPM 2.0 supported by the U-Boot drivers
by an enabled U-Boot driver.
- CONFIG_TPM=y
CONFIG_TPM_V2=y is required?
Best regards
Heinrich
Thanks /Ilias