With TPM 1.2, the ACPI table ("TCPA") has two fields to recover the Event
Log Area (LAML and LASA). These logs are useful to understand and rebuild
the final values of PCRs.
With TPM 2.0, the ACPI table ("TPM2") does not contain these fields
anymore. The recommended method is now to call the GetEventLog EFI
protocol before ExitBootServices.
Implement this method within the EFI stub and create a copy of the logs
for the TPM device using a Linux-specific EFI configuration table
(LINUX_EFI_TPM_EVENT_LOG). This will create
/sys/kernel/security/tpm0/binary_bios_measurements for TPM 2.0 devices
(similarly to the current behaviour for TPM 1.2 devices).
Two formats for the log entries exist: TPM 1.2 (SHA1) and TPM 2.0 (Crypto
Agile). This patch set only retrieves the first type of logs. The second
type will be implemented in a subsequent patch set.
According to the specifications[1], once GetEventLog has been called,
future events shall be stored in a separate EFI configuration table
(EFI_TCG2_FINAL_EVENTS_TABLE). Events stored in this table are not
processed in this patch set as they are stored in the Crypto Agile format.
These could eventually be merged with the new table for a unified view
of the logs from userspace.
[1] TCG EFI Protocol Specification, Revision 00.13, March 30, 2016
https://trustedcomputinggroup.org/wp-content/uploads/EFI-Protocol-Specification-rev13-160330final.pdf
-------------------------------------------------------------------------------
Patchset Changelog:
Version 3:
- Move event log providers (acpi and of) to tpm_eventlog_*.c
- Move efi changes from PATCH 3 to PATCH 2
- Change return value of tpm_read_log_acpi and tpm_read_log_of
- Change iounmap to memunmap calls
- Use log_tbl as variable name for consistency
- Fix kbuild failures
Version 2:
- Move tpm_eventlog.h to top include directory, add commit for this.
- Use EFI_LOADER_DATA to store the configuration table
- Whitespace and new lines fixes
Thiebaud Weksteen (5):
tpm: move tpm_eventlog.h outside of drivers folder
tpm: rename event log provider files
tpm: add event log format version
efi: call get_event_log before ExitBootServices
tpm: parse TPM event logs based on EFI table
arch/x86/boot/compressed/eboot.c | 1 +
drivers/char/tpm/Makefile | 5 +-
drivers/char/tpm/tpm-chip.c | 3 +-
drivers/char/tpm/tpm-interface.c | 2 +-
drivers/char/tpm/tpm.h | 35 ++++++++--
drivers/char/tpm/tpm1_eventlog.c | 13 +++-
drivers/char/tpm/tpm2_eventlog.c | 2 +-
.../char/tpm/{tpm_acpi.c => tpm_eventlog_acpi.c} | 4 +-
drivers/char/tpm/tpm_eventlog_efi.c | 66 ++++++++++++++++++
drivers/char/tpm/{tpm_of.c => tpm_eventlog_of.c} | 6 +-
drivers/firmware/efi/Makefile | 2 +-
drivers/firmware/efi/efi.c | 4 ++
drivers/firmware/efi/libstub/Makefile | 3 +-
drivers/firmware/efi/libstub/tpm.c | 81 ++++++++++++++++++++++
drivers/firmware/efi/tpm.c | 40 +++++++++++
include/linux/efi.h | 46 ++++++++++++
{drivers/char/tpm => include/linux}/tpm_eventlog.h | 35 +++-------
17 files changed, 304 insertions(+), 44 deletions(-)
rename drivers/char/tpm/{tpm_acpi.c => tpm_eventlog_acpi.c} (97%)
create mode 100644 drivers/char/tpm/tpm_eventlog_efi.c
rename drivers/char/tpm/{tpm_of.c => tpm_eventlog_of.c} (93%)
create mode 100644 drivers/firmware/efi/tpm.c
rename {drivers/char/tpm => include/linux}/tpm_eventlog.h (77%)
--
2.14.1.821.g8fa685d3b7-goog
