On Wed, Jul 08, 2020 at 12:13:13PM -0400, Mimi Zohar wrote:
Hi Sasha,
On Wed, 2020-07-08 at 11:40 -0400, Sasha Levin wrote:
From: Maurizio Drocco maurizio.drocco@ibm.com
[ Upstream commit 20c59ce010f84300f6c655d32db2610d3433f85c ]
Registers 8-9 are used to store measurements of the kernel and its command line (e.g., grub2 bootloader with tpm module enabled). IMA should include them in the boot aggregate. Registers 8-9 should be only included in non-SHA1 digests to avoid ambiguity.
Prior to Linux 5.8, the SHA1 template data hashes were padded before being extended into the TPM. Support for calculating and extending the per TPM bank template data digests is only being upstreamed in Linux 5.8.
How will attestation servers know whether to include PCRs 8 & 9 in the the boot_aggregate calculation? Now, there is a direct relationship between the template data SHA1 padded digest not including PCRs 8 & 9, and the new per TPM bank template data digest including them.
Got it, I'll drop it then, thank you!