security/tpm: improve tlcl_extend() signature

Until now tcg-2.0/tss.c was just assuming certain buffer size and
hash algorithm. Change it to accept digest type, which the call sites
know.

Also drop `uint8_t *out_digest` parameter which was always `NULL`
and was handled only by tcg-1.2 code.

Change-Id: I944302b502e3424c5041b17c713a867b0fc535c4
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68745
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Frans Hendriks <fhendriks@eltan.com>

1 files changed, 7 insertions, 12 deletions

diff --git a/src/security/tpm/tss/tcg-1.2/tss.c b/src/security/tpm/tss/tcg-1.2/tss.c
index 52bc2722b2..6b79aabe87 100644
--- a/src/security/tpm/tss/tcg-1.2/tss.c
+++ b/src/security/tpm/tss/tcg-1.2/tss.c
@@ -331,25 +331,20 @@ uint32_t tlcl_set_global_lock(void)
 	return tlcl_write(TPM_NV_INDEX0, NULL, 0);
 }
 
-uint32_t tlcl_extend(int pcr_num, const uint8_t *in_digest,
-		     uint8_t *out_digest)
+uint32_t tlcl_extend(int pcr_num, const uint8_t *digest_data,
+		     enum vb2_hash_algorithm digest_algo)
 {
 	struct s_tpm_extend_cmd cmd;
 	uint8_t response[kTpmResponseHeaderLength + kPcrDigestLength];
-	uint32_t result;
+
+	if (digest_algo != VB2_HASH_SHA1)
+		return TPM_E_INVALID_ARG;
 
 	memcpy(&cmd, &tpm_extend_cmd, sizeof(cmd));
 	to_tpm_uint32(cmd.buffer + tpm_extend_cmd.pcrNum, pcr_num);
-	memcpy(cmd.buffer + cmd.inDigest, in_digest, kPcrDigestLength);
-
-	result = tlcl_send_receive(cmd.buffer, response, sizeof(response));
-	if (result != TPM_SUCCESS)
-		return result;
+	memcpy(cmd.buffer + cmd.inDigest, digest_data, kPcrDigestLength);
 
-	if (out_digest)
-		memcpy(out_digest, response + kTpmResponseHeaderLength,
-		       kPcrDigestLength);
-	return result;
+	return tlcl_send_receive(cmd.buffer, response, sizeof(response));
 }
 
 uint32_t tlcl_get_permissions(uint32_t index, uint32_t *permissions)