On 23/06/16 03:02, Thiago Jung Bauermann wrote: > Hello Balbir, > Hi Thiago >>> 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
