security/vboot: Add interface for FSP 2.0 mrc caching

* Move vboot/tpm specific implementation to vboot.
* Only call functions if CONFIG_FSP2_0_USES_TPM_MRC_HASH is set.
* Preparation for software hash function support, no logic changed.

Change-Id: I41a458186c7981adaf3fea8974adec2ca8668f14
Signed-off-by: Philipp Deppenwiese <zaolin@das-labor.org>
Reviewed-on: https://review.coreboot.org/24904
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

2 files changed, 117 insertions, 0 deletions

diff --git a/src/security/vboot/Makefile.inc b/src/security/vboot/Makefile.inc
index 75c2a9e44c..b542425346 100644
--- a/src/security/vboot/Makefile.inc
+++ b/src/security/vboot/Makefile.inc
@@ -78,6 +78,8 @@ romstage-y += vboot_handoff.c common.c
 ramstage-y += common.c
 postcar-y += common.c
 
+romstage-$(CONFIG_FSP2_0_USES_TPM_MRC_HASH) += mrc_cache_hash_tpm.c
+
 ifeq ($(CONFIG_VBOOT_SEPARATE_VERSTAGE),y)
 VB_FIRMWARE_ARCH := $(ARCHDIR-$(ARCH-verstage-y))
 else
diff --git a/src/security/vboot/mrc_cache_hash_tpm.c b/src/security/vboot/mrc_cache_hash_tpm.c
new file mode 100644
index 0000000000..d54f8f4618
--- /dev/null
+++ b/src/security/vboot/mrc_cache_hash_tpm.c
@@ -0,0 +1,115 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2018 Facebook Inc
+ * Copyright (C) 2015-2016 Intel Corp.
+ * (Written by Andrey Petrov <andrey.petrov@intel.com> for Intel Corp.)
+ * (Written by Alexandru Gagniuc <alexandrux.gagniuc@intel.com> for Intel Corp.)
+ *
+ * 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/vboot/antirollback.h>
+#include <program_loading.h>
+#include <security/vboot/vboot_common.h>
+#include <vb2_api.h>
+#include <security/tpm/tss.h>
+#include <fsp/memory_init.h>
+#include <console/console.h>
+#include <string.h>
+
+void mrc_cache_update_hash(const uint8_t *data, size_t size)
+{
+	uint8_t data_hash[VB2_SHA256_DIGEST_SIZE];
+	static const uint8_t dead_hash[VB2_SHA256_DIGEST_SIZE] = {
+		0xba, 0xad, 0xda, 0x1a, /* BAADDA1A */
+		0xde, 0xad, 0xde, 0xad, /* DEADDEAD */
+		0xde, 0xad, 0xda, 0x1a, /* DEADDA1A */
+		0xba, 0xad, 0xba, 0xad, /* BAADBAAD */
+		0xba, 0xad, 0xda, 0x1a, /* BAADDA1A */
+		0xde, 0xad, 0xde, 0xad, /* DEADDEAD */
+		0xde, 0xad, 0xda, 0x1a, /* DEADDA1A */
+		0xba, 0xad, 0xba, 0xad, /* BAADBAAD */
+	};
+	const uint8_t *hash_ptr = data_hash;
+
+	/* We do not store normal mode data hash in TPM. */
+	if (!vboot_recovery_mode_enabled())
+		return;
+
+	/* Initialize TPM driver. */
+	if (tlcl_lib_init() != VB2_SUCCESS) {
+		printk(BIOS_ERR, "MRC: TPM driver initialization failed.\n");
+		return;
+	}
+
+	/* Calculate hash of data generated by MRC. */
+	if (vb2_digest_buffer(data, size, VB2_HASH_SHA256, data_hash,
+			      sizeof(data_hash))) {
+		printk(BIOS_ERR, "MRC: SHA-256 calculation failed for data. "
+		       "Not updating TPM hash space.\n");
+		/*
+		 * Since data is being updated in recovery cache, the hash
+		 * currently stored in TPM recovery hash space is no longer
+		 * valid. If we are not able to calculate hash of the data being
+		 * updated, reset all the bits in TPM recovery hash space to
+		 * pre-defined hash pattern.
+		 */
+		hash_ptr = dead_hash;
+	}
+
+	/* Write hash of data to TPM space. */
+	if (antirollback_write_space_rec_hash(hash_ptr, VB2_SHA256_DIGEST_SIZE)
+	    != TPM_SUCCESS) {
+		printk(BIOS_ERR, "MRC: Could not save hash to TPM.\n");
+		return;
+	}
+
+	printk(BIOS_INFO, "MRC: TPM MRC hash updated successfully.\n");
+}
+
+int mrc_cache_verify_hash(const uint8_t *data, size_t size)
+{
+	uint8_t data_hash[VB2_SHA256_DIGEST_SIZE];
+	uint8_t tpm_hash[VB2_SHA256_DIGEST_SIZE];
+
+	/* We do not store normal mode data hash in TPM. */
+	if (!vboot_recovery_mode_enabled())
+		return 1;
+
+	/* Calculate hash of data read from RECOVERY_MRC_CACHE. */
+	if (vb2_digest_buffer(data, size, VB2_HASH_SHA256, data_hash,
+			      sizeof(data_hash))) {
+		printk(BIOS_ERR, "MRC: SHA-256 calculation failed for data.\n");
+		return 0;
+	}
+
+	/* Initialize TPM driver. */
+	if (tlcl_lib_init() != VB2_SUCCESS) {
+		printk(BIOS_ERR, "MRC: TPM driver initialization failed.\n");
+		return 0;
+	}
+
+	/* Read hash of MRC data saved in TPM. */
+	if (antirollback_read_space_rec_hash(tpm_hash, sizeof(tpm_hash))
+	    != TPM_SUCCESS) {
+		printk(BIOS_ERR, "MRC: Could not read hash from TPM.\n");
+		return 0;
+	}
+
+	if (memcmp(tpm_hash, data_hash, sizeof(tpm_hash))) {
+		printk(BIOS_ERR, "MRC: Hash comparison failed.\n");
+		return 0;
+	}
+
+	printk(BIOS_INFO, "MRC: Hash comparison successful. "
+	       "Using data from RECOVERY_MRC_CACHE\n");
+	return 1;
+}