On Thu, May 30, 2024 at 07:16:56PM -0700, Eric Biggers wrote:
On Thu, May 30, 2024 at 06:03:18PM -0700, Ross Philipson wrote:
From: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>
For better or worse, Secure Launch needs SHA-1 and SHA-256. The
choice of hashes used lie with the platform firmware, not with
software, and is often outside of the users control.
Even if we'd prefer to use SHA-256-only, if firmware elected to start us
with the SHA-1 and SHA-256 backs active, we still need SHA-1 to parse
the TPM event log thus far, and deliberately cap the SHA-1 PCRs in order
to safely use SHA-256 for everything else.
The SHA-1 code here has its origins in the code from the main kernel:
commit c4d5b9ffa31f ("crypto: sha1 - implement base layer for SHA-1")
A modified version of this code was introduced to the lib/crypto/sha1.c
to bring it in line with the SHA-256 code and allow it to be pulled into the
setup kernel in the same manner as SHA-256 is.
Signed-off-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ross Philipson <ross.philipson@xxxxxxxxxx>
Thanks. This explanation doesn't seem to have made it into the actual code or
documentation. Can you please get it into a more permanent location?
I see that a new version of the patchset was sent out but this suggestion was
not taken. Are you planning to address it?
- Eric