From 31839f3c45d71ac03688cc7719287798eafb0996 Mon Sep 17 00:00:00 2001 From: Andrey Pronin Date: Thu, 19 Sep 2019 09:27:23 -0700 Subject: vboot: extend BOOT_MODE_PCR to SHA256 bank on TPM2 With the support of various algorithms and banks in tlcl_extend(), digest_algo parameter of tpm_extend_pcr() started defining the target PCR bank in TPM2 case. The OS expects coreboot to extend the SHA256 bank of BOOT_MODE_PCR. The value that the OS expects coreboot to extend into BOOT_MODE_PCR is the SHA1 digest of mode bits extended to the length of SHA256 digest by appending zero bytes. Thus the correct value for digest_algo passed into tpm_extend_pcr() for BOOT_MODE_PCR is TPM_ALG_SHA256. This didn't matter until adding the support for multiple digest introduced by patches like https://review.coreboot.org/c/coreboot/+/33252, as tlcl_extend always used SHA256 bank before. Change-Id: I834fec24023cd10344cc359117f00fc80c61b80c Signed-off-by: Andrey Pronin Reviewed-on: https://review.coreboot.org/c/coreboot/+/35476 Reviewed-by: Julius Werner Tested-by: build bot (Jenkins) --- src/security/vboot/tpm_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/security/vboot/tpm_common.c') diff --git a/src/security/vboot/tpm_common.c b/src/security/vboot/tpm_common.c index 1db7189d7a..0a211c57d4 100644 --- a/src/security/vboot/tpm_common.c +++ b/src/security/vboot/tpm_common.c @@ -46,7 +46,7 @@ vb2_error_t vboot_extend_pcr(struct vb2_context *ctx, int pcr, switch (which_digest) { /* SHA1 of (devmode|recmode|keyblock) bits */ case BOOT_MODE_PCR: - return tpm_extend_pcr(pcr, VB2_HASH_SHA1, buffer, size, + return tpm_extend_pcr(pcr, VB2_HASH_SHA256, buffer, size, TPM_PCR_BOOT_MODE); /* SHA256 of HWID */ case HWID_DIGEST_PCR: -- cgit v1.2.3