On Mon, May 22, 2017 at 09:21:28AM +0200, Roberto Sassu wrote: > On 5/20/2017 3:22 PM, Jarkko Sakkinen wrote: > > On Mon, May 15, 2017 at 04:22:22PM +0200, Roberto Sassu wrote: > > > On 5/15/2017 1:16 PM, Jarkko Sakkinen wrote: > > > > On Fri, May 05, 2017 at 04:21:49PM +0200, Roberto Sassu wrote: > > > > > tpm_pcr_algorithms() returns to its callers the IDs of the hash > > > > > algorithms > > > > > supported by the TPM. This patch introduces tpm_pcr_algo_to_crypto(), > > > > > so that the callers can use the crypto subsystem to calculate the > > > > > digest > > > > > to be passed to tpm_pcr_extend(). > > > > > > > > > > tpm_pcr_algo_from_crypto(), implemented for completeness, is instead > > > > > used > > > > > > > > What do you mean by completeness? Please, never add unused stuff. > > > > > > > > > by tpm2_seal_trusted() to perform the opposite conversion. > > > > > > > > > > Signed-off-by: Roberto Sassu <roberto.sa...@huawei.com> > > > > > --- > > > > > v2 > > > > > > > > > > - fixed return values of tpm2_pcr_algo_to_crypto() and > > > > > tpm2_pcr_algo_from_crypto() if TPM support is disabled in the kernel > > > > > > > > Change Log only to the cover letter. > > > > > > > > > drivers/char/tpm/tpm-interface.c | 51 > > > > > ++++++++++++++++++++++++++++++++++++++++ > > > > > drivers/char/tpm/tpm2-cmd.c | 42 > > > > > +++++++++------------------------ > > > > > include/linux/tpm.h | 13 ++++++++++ > > > > > 3 files changed, 75 insertions(+), 31 deletions(-) > > > > > > > > This commit is just deadly wrong in so many ways. > > > > > > > > I would suggest to make extend always just take crypto ID in so you > > > > don't have to add these bizarre conversion functions. > > > > > > The reason of this choice (as I explained in the cover letter) > > > is that TPM users might want to produce an event log with > > > the TCG format (which includes the TPM algorithm ID). Also, > > > TPM IDs should be preferred because, with them, TPM users > > > can calculate a digest directly with the TPM. > > > > > > Taking crypto IDs means relying on the fact that there > > > is always a mapping between TPM IDs and crypto IDs. > > > Otherwise, tpm_pcr_algorithms() cannot return the algorithms > > > to its callers and PCRs cannot be extended. If TPM IDs are used, > > > TPM users have two alternatives: calculate the digest with > > > the TPM, or pass a SHA1 digest to tpm_pcr_extend(), so that > > > it can be padded to extend remanining PCR banks. > > > > > > However, this second option will work only when the TPM driver > > > determines the size of an algorithm without relying on the crypto > > > subsystem. At the moment, if a TPM ID is not mapped to a crypto ID, > > > tpm2_pcr_extend() ignores the digest. > > > > > > Roberto > > > > What if tpm_pcr_algorithms would convert TPM IDs to crypto IDs? > > > > Externally other subsystems would have to then deal with only crypto > > IDs. > > Then, other subsystems cannot: > > - use the TPM to calculate a digest > - create an event log with the TCG format > > Roberto
Can you open this up a bit? What is the use case that you canno implement? /Jarkko ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ tpmdd-devel mailing list tpmdd-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tpmdd-devel