On Mon, Nov 30, 2020 at 10:13:02PM -0500, Mimi Zohar wrote:
On Mon, 2020-11-30 at 19:21 -0500, Sasha Levin wrote:On Sun, Nov 29, 2020 at 08:17:38AM -0500, Mimi Zohar wrote: >Hi Sasha, > >On Wed, 2020-07-08 at 21:27 -0400, Sasha Levin wrote: >> 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@xxxxxxx> >> >> >> >> [ 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! > >After re-thinking this over, I realized that the attestation server can >verify the "boot_aggregate" based on the quoted PCRs without knowing >whether padded SHA1 hashes or per TPM bank hash values were extended >into the TPM[1], but non-SHA1 boot aggregate values [2] should always >include PCRs 8 & 9. > >Any place commit 6f1a1d103b48 was backported [2], this commit >20c59ce010f8 ("ima: extend boot_aggregate with kernel measurements") >should be backported as well. Which kernels should it apply to? 5.7 is EOL now, so I looked at 5.4 but it doesn't apply cleanly there.For 5.4, both "git cherry-pick" and "git am --3way" for 20c59ce010f8 seem to work.
You're right, I've grabbed it too. Thanks! -- Thanks, Sasha
