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Merge tag 'tpmdd-next-20190625' of git://git.infradead.org/users/jjs/linux-tpmdd
Pull tpm updates from Jarkko Sakkinen:
"This contains two critical bug fixes and support for obtaining TPM
events triggered by ExitBootServices().
For the latter I have to give a quite verbose explanation not least
because I had to revisit all the details myself to remember what was
going on in Matthew's patches.
The preboot software stack maintains an event log that gets entries
every time something gets hashed to any of the PCR registers. What
gets hashed could be a component to be run or perhaps log of some
actions taken just to give couple of coarse examples. In general,
anything relevant for the boot process that the preboot software does
gets hashed and a log entry with a specific event type [1].
The main application for this is remote attestation and the reason why
it is useful is nicely put in the very first section of [1]:
"Attestation is used to provide information about the platform’s
state to a challenger. However, PCR contents are difficult to
interpret; therefore, attestation is typically more useful when
the PCR contents are accompanied by a measurement log. While not
trusted on their own, the measurement log contains a richer set of
information than do the PCR contents. The PCR contents are used to
provide the validation of the measurement log."
Because EFI_TCG2_PROTOCOL.GetEventLog() is not available after calling
ExitBootServices(), Linux EFI stub copies the event log to a custom
configuration table. Unfortunately, ExitBootServices() also generates
events and obviously these events do not get copied to that table.
Luckily firmware does this for us by providing a configuration table
identified by EFI_TCG2_FINAL_EVENTS_TABLE_GUID.
This essentially contains necessary changes to provide the full event
log for the use the user space that is concatenated from these two
partial event logs [2]"
[1] https://trustedcomputinggroup.org/resource/pc-client-specific-platform-firmware-profile-specification/
[2] The final concatenation is done in drivers/char/tpm/eventlog/efi.c
* tag 'tpmdd-next-20190625' of git://git.infradead.org/users/jjs/linux-tpmdd:
tpm: Don't duplicate events from the final event log in the TCG2 log
Abstract out support for locating an EFI config table
tpm: Fix TPM 1.2 Shutdown sequence to prevent future TPM operations
efi: Attempt to get the TCG2 event log in the boot stub
tpm: Append the final event log to the TPM event log
tpm: Reserve the TPM final events table
tpm: Abstract crypto agile event size calculations
tpm: Actually fail on TPM errors during "get random"
884922591e