On 23/06/16 03:02, Thiago Jung Bauermann wrote:

Hello Balbir,

Hi Thiago
 

quoted

quoted

3. have IMA pass-on its event log (where integrity measurements are

   registered) accross kexec to the second kernel, so that the event
   history is preserved.

OK.. and this is safe? Do both the kernels need to be signed by the
same certificate?

They don't. The integrity of the event log (assuming that is what you mean 
by "this" in "this is safe") is guaranteed by the TPM device. Each event in 
the measurement list extends a PCR and records its PCR value. It is 
cryptographically guaranteed that if you replay the PCR extends recorded in 
the event log and in the end of the process they match the current PCR 
values in the TPM device, then that event log is correct.

What I meant was how does the new kernel know that the old kernel did not
cheat while passing on the values? I presume because we trust that kernel
via a signature.


and

How do we know the new kernel is safe to load - I guess via a signature that
the new kernel is signed with (assuming it is present in the key ring).

Balbir Singh