refactor(measured-boot): mb algorithm selection
With RSS now introduced, we have 2 Measured Boot backends. Both backends
can be used in the same firmware build with potentially different hash
algorithms, so now there can be more than one hash algorithm in a build.
Therefore the logic for selecting the measured boot hash algorithm needs
to be updated and the coordination of algorithm selection added. This is
done by:
- Adding MBOOT_EL_HASH_ALG for Event Log to define the hash algorithm
to replace TPM_HASH_ALG, removing reference to TPM.
- Adding MBOOT_RSS_HASH_ALG for RSS to define the hash algorithm to
replace TPM_HASH_ALG.
- Coordinating MBOOT_EL_HASH_ALG and MBOOT_RSS_HASH_ALG to define the
Measured Boot configuration macros through defining
TF_MBEDTLS_MBOOT_USE_SHA512 to pull in SHA-512 support if either
backend requires a stronger algorithm than SHA-256.
Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
Change-Id: I4ddf06ebdc3835beb4d1b6c7bab5a257ffc5c71a
diff --git a/drivers/measured_boot/rss/rss_measured_boot.mk b/drivers/measured_boot/rss/rss_measured_boot.mk
index 01545af..18ee836 100644
--- a/drivers/measured_boot/rss/rss_measured_boot.mk
+++ b/drivers/measured_boot/rss/rss_measured_boot.mk
@@ -6,21 +6,18 @@
# Hash algorithm for measured boot
# SHA-256 (or stronger) is required.
-# TODO: The measurement algorithm incorrectly suggests that the TPM backend
-# is used which may not be the case. It is currently being worked on and
-# soon TPM_HASH_ALG will be replaced by a more generic name.
-TPM_HASH_ALG := sha256
+MBOOT_RSS_HASH_ALG := sha256
-ifeq (${TPM_HASH_ALG}, sha512)
+ifeq (${MBOOT_RSS_HASH_ALG}, sha512)
MBOOT_ALG_ID := MBOOT_ALG_SHA512
MBOOT_DIGEST_SIZE := 64U
-else ifeq (${TPM_HASH_ALG}, sha384)
+else ifeq (${MBOOT_RSS_HASH_ALG}, sha384)
MBOOT_ALG_ID := MBOOT_ALG_SHA384
MBOOT_DIGEST_SIZE := 48U
else
MBOOT_ALG_ID := MBOOT_ALG_SHA256
MBOOT_DIGEST_SIZE := 32U
-endif #TPM_HASH_ALG
+endif #MBOOT_RSS_HASH_ALG
# Set definitions for Measured Boot driver.
$(eval $(call add_defines,\