On 5/31/23 18:43, Mimi Zohar wrote:
On Wed, 2023-05-31 at 15:02 -0700, Tushar Sugandhi wrote:
Hi Mimi,
On 5/31/23 04:39, Mimi Zohar wrote:
Hi Tushar,
On Thu, 2023-05-25 at 10:21 -0700, Tushar Sugandhi wrote:
The issue of IMA measurements getting lost between kexec 'load' and 'execute' still exists.
I verified it on the mainline kernel 6.4.rc3. See *Appendix A* for details.
I think there's a 2nd problem. Once the IMA measurement list is frozen (at kexec 'exec' stage)
IMA must stop extending PCRs. It can log (into the void) if it wanted to but the PCR extensions
have to stop otherwise the TPM's PCR state won't match the log in the kexec'ed-to kernel. I have
seen that on PPC64 some processes are being kicked off by kexec 'exec' that end up causing TPM
driver error message due to what seems to be a shutdown of the driver subsystem at this point.
I am not sure what an elegant method would be to stop PCR extensions. Maybe a flag on the level
of IMA would do? Or notifying the TPM driver to reject PCR extensions or just any command?
Stefan
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