security/vboot: Add Support for Intel PTT

Add support for Intel PTT. For supporting Intel PTT we need to disable
read and write access to the TPM NVRAM during the bootblock. TPM NVRAM
will only be available once the DRAM is initialized. To circumvent this,
we mock secdata if HAVE_INTEL_PTT is set. The underlying problem is,
that the iTPM only supports a stripped down instruction set while the
Intel ME is not fully booted up. Details can be found in Intel document
number 571993 - Paragraph 2.10.

Change-Id: I08c9a839f53f96506be5fb68f7c1ed5bf6692505
Signed-off-by: Christian Walter <christian.walter@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34510
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>

1 files changed, 58 insertions, 0 deletions

diff --git a/src/security/vboot/tpm_common.c b/src/security/vboot/tpm_common.c
new file mode 100644
index 0000000000..1a07ef6def
--- /dev/null
+++ b/src/security/vboot/tpm_common.c
@@ -0,0 +1,58 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+
+#include <security/tpm/tspi.h>
+#include <vb2_api.h>
+#include <security/vboot/tpm_common.h>
+
+#define TPM_PCR_BOOT_MODE "VBOOT: boot mode"
+#define TPM_PCR_GBB_HWID_NAME "VBOOT: GBB HWID"
+
+uint32_t vboot_setup_tpm(struct vb2_context *ctx)
+{
+	uint32_t result;
+
+	result = tpm_setup(ctx->flags & VB2_CONTEXT_S3_RESUME);
+	if (result == TPM_E_MUST_REBOOT)
+		ctx->flags |= VB2_CONTEXT_SECDATA_WANTS_REBOOT;
+
+	return result;
+}
+
+uint32_t vboot_extend_pcr(struct vb2_context *ctx, int pcr,
+			  enum vb2_pcr_digest which_digest)
+{
+	uint8_t buffer[VB2_PCR_DIGEST_RECOMMENDED_SIZE];
+	uint32_t size = sizeof(buffer);
+	int rv;
+
+	rv = vb2api_get_pcr_digest(ctx, which_digest, buffer, &size);
+	if (rv != VB2_SUCCESS)
+		return rv;
+	if (size < TPM_PCR_MINIMUM_DIGEST_SIZE)
+		return VB2_ERROR_UNKNOWN;
+
+	switch (which_digest) {
+	/* SHA1 of (devmode|recmode|keyblock) bits */
+	case BOOT_MODE_PCR:
+		return tpm_extend_pcr(pcr, VB2_HASH_SHA1, buffer, size,
+				      TPM_PCR_BOOT_MODE);
+	 /* SHA256 of HWID */
+	case HWID_DIGEST_PCR:
+		return tpm_extend_pcr(pcr, VB2_HASH_SHA256, buffer,
+					  size, TPM_PCR_GBB_HWID_NAME);
+	default:
+		return VB2_ERROR_UNKNOWN;
+	}
+}