security/intel/cbnt: Generate KM from Kconfig symbols

Add an option to generate the Key Manifest from Kconfig options.

Change-Id: I3a448f37c81148625c7879dcb64da4d517567067
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50410
Reviewed-by: Christian Walter <christian.walter@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

2 files changed, 62 insertions, 1 deletions

diff --git a/src/security/intel/cbnt/Kconfig b/src/security/intel/cbnt/Kconfig
index 8c4d999043..0f4c2167c9 100644
--- a/src/security/intel/cbnt/Kconfig
+++ b/src/security/intel/cbnt/Kconfig
@@ -21,13 +21,22 @@ config INTEL_CBNT_GENERATE_KM
 	default y
 	select INTEL_CBNT_NEED_KM_PUB_KEY
 	select INTEL_CBNT_NEED_KM_PRIV_KEY
+	select INTEL_CBNT_NEED_BPM_PUB_KEY if !INTEL_CBNT_BG_PROV_KM_USE_CFG_FILE
 	help
 	  Select y to generate the Key Manifest (KM).
 	  Select n to include a KM binary.
 
+config INTEL_CBNT_BG_PROV_KM_USE_CFG_FILE
+	bool "KM: use a CBnT json config file"
+	depends on INTEL_CBNT_GENERATE_KM
+	default y
+	help
+	  Select y to generate KM from a json config file.
+	  Select n to generate KM from Kconfig options
+
 config INTEL_CBNT_BG_PROV_CFG_FILE
 	string "CBnT json config file"
-	depends on INTEL_CBNT_GENERATE_KM
+	depends on INTEL_CBNT_BG_PROV_KM_USE_CFG_FILE
 	help
 	  Location of the bg-prov json config file.
 	  Either get a sample JSON config file:
@@ -71,6 +80,45 @@ config INTEL_CBNT_BPM_PRIV_KEY_FILE
 	help
 	  Location of the boot policy manifest (BPM) private key file in .pem format.
 
+if !INTEL_CBNT_BG_PROV_KM_USE_CFG_FILE && INTEL_CBNT_GENERATE_KM
+
+menu "KM options"
+
+config INTEL_CBNT_KM_REVISION
+	int "KM revision"
+	default 1
+	help
+	  Version of the Key Manifest defined by the Platform Manufacturer.
+	  The actual value is transparent to Boot Guard and is not processed by Boot Guard.
+
+config INTEL_CBNT_KM_SVN
+	int "KM security Version Number"
+	range 0 15
+	default 0
+	help
+	  This value is determined by the Platform Manufacturer.
+	  Boot Guard uses this to compare it to the Key Manifest
+	  Revocation Value (Revocation.KMSVN) in FPF.
+
+	  If KMSVN < Revocation.KMSVN, the KM will be revoked. It will trigger ENF (the
+	  enforcement policy).
+	  IF KMSVN > Revocation.KMSVN, the Revocation.KMSVN will be set to the KMSVN.
+
+	  Note: Once the value reaches 0Fh, revocation saturates and one can no longer
+	  revoke newer KMs.
+
+config INTEL_CBNT_KM_ID
+	int "KM ID"
+	default 1
+	help
+	  This identifies the Key Manifest to be used for a platform.
+	  This must match the Key Manifest Identifier programmed in
+	  the field programmable fuses.
+
+endmenu
+
+endif # !INTEL_CBNT_BG_PROV_KM_USE_CFG_FILE
+
 config INTEL_CBNT_KEY_MANIFEST_BINARY
 	string "KM (Key Manifest) binary location"
 	depends on !INTEL_CBNT_GENERATE_KM
diff --git a/src/security/intel/cbnt/Makefile.inc b/src/security/intel/cbnt/Makefile.inc
index b508974283..62b12f0c0f 100644
--- a/src/security/intel/cbnt/Makefile.inc
+++ b/src/security/intel/cbnt/Makefile.inc
@@ -44,9 +44,22 @@ $(call add_intermediate, add_bpm_fit, $(IFITTOOL) set_fit_ptr)
 endif
 
 ifeq ($(CONFIG_INTEL_CBNT_GENERATE_KM),y)
+ifeq ($(CONFIG_INTEL_CBNT_BG_PROV_KM_USE_CFG_FILE),y)
 $(obj)/km_unsigned.bin: $(obj)/km_pub.pem $(BG_PROV) $(CBNT_CFG)
 	printf "    BG_PROV    creating unsigned KM using config file\n"
 	$(BG_PROV) km-gen $@ $< --config=$(CBNT_CFG)
+else
+PK_HASH_ALG_SHA256:=11 # Hardcode as no other options are available for CBnT
+$(obj)/km_unsigned.bin: $(obj)/km_pub.pem $(obj)/bpm_pub.pem $(BG_PROV)
+	printf "    BG_PROV    creating unsigned KM\n"
+	$(BG_PROV) km-gen $@ $< --revision=$(CONFIG_INTEL_CBNT_KM_REVISION) \
+				--svn=$(CONFIG_INTEL_CBNT_KM_SVN) \
+				--id=$(CONFIG_INTEL_CBNT_KM_ID) \
+				--pkhashalg=$(PK_HASH_ALG_SHA256) \
+				--bpmpubkey=$(obj)/bpm_pub.pem \
+				--bpmhashalgo=$(PK_HASH_ALG_SHA256) \
+				--out=$(obj)/km_cfg.json
+endif
 
 $(obj)/km.bin: $(obj)/km_unsigned.bin $(BG_PROV) $(call strip_quotes, $(CONFIG_INTEL_CBNT_KM_PRIV_KEY_FILE))
 	printf "    BG_PROV    signing KM\n"