At last year's plumbers conference it was agreed in principle to export TPM 2 PCRs via sysfs. We also agreed we should conform to sysfs rules of one value per file, which rules out the "pcrs" file format of TPM 1.2 which has every PCR value in the same file. I added these files using device groups, so one group per bank hash of the TPM. Using an emulator which supports a variety of hashes, you can see the structure of the group files: root@testdeb:~# ls -F /sys/class/tpm/tpm0/ dev pcr-sha1/ pcr-sha384/ power/ tpm_version_major device@ pcr-sha256/ pcr-sha512/ subsystem@ uevent As a future enhancement, we could use the group is_visible function to remove files corresponding to PCRs which don't exist. The reason this isn't present is that so far I've never seen a TPM with a missing PCR. James --- James Bottomley (1): tpm: add sysfs exports for all banks of PCR registers drivers/char/tpm/tpm-sysfs.c | 178 +++++++++++++++++++++++++++++++++++ include/linux/tpm.h | 8 +- 2 files changed, 185 insertions(+), 1 deletion(-) -- 2.26.2
