On Thu, Oct 03, 2019 at 02:32:11PM +0300, Jarkko Sakkinen wrote: > On Wed, Oct 02, 2019 at 08:40:24AM -0400, Mimi Zohar wrote: > > On Thu, 2019-09-26 at 16:12 +0300, Jarkko Sakkinen wrote: > > > On Thu, Sep 26, 2019 at 03:46:35PM +0300, Jarkko Sakkinen wrote: > > > > On Wed, Sep 25, 2019 at 04:48:41PM +0300, Jarkko Sakkinen wrote: > > > > > - tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_RANDOM); > > > > > + tpm_buf_reset(&buf, data_ptr, PAGE_SIZE, > > > > > + TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_EXTEND); > > > > > > > > Oops. > > > > > > Maybe we could use random as the probe for TPM version since we anyway > > > send a TPM command as a probe for TPM version: > > > > > > 1. Try TPM2 get random. > > > 2. If fail, try TPM1 get random. > > > 3. Output random number to klog. > > > > > > Something like 8 bytes would be sufficient. This would make sure that > > > no new change breaks tpm_get_random() and also this would give some > > > feedback that TPM is at least somewhat working. > > > > That involves sending 2 TPM commands. At what point does this occur? > > On registration? Whenever getting a random number? Is the result > > cached in chip->flags? > > On registeration. It is just printed to klog. > > > Will this delay the TPM initialization, causing IMA to go into "TPM > > bypass mode"? > > Of course it will delay the init. > > As I've stated before the real fix for the bypass issue would be > to make TPM as part of the core but this has not received much > appeal. I think I've sent patch for this once. It has been like that people reject a fix to a race condition and then I get complains on adding minor latency to the init because of the existing race. It is ridicilous, really. /Jarkko
