1 files changed, 737 insertions, 0 deletions

diff --git a/roms/skiboot/libstb/secvar/storage/secboot_tpm.c b/roms/skiboot/libstb/secvar/storage/secboot_tpm.c
new file mode 100644
index 000000000..129f674af
--- /dev/null
+++ b/roms/skiboot/libstb/secvar/storage/secboot_tpm.c
@@ -0,0 +1,737 @@
+// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+/* Copyright 2020 IBM Corp. */
+#ifndef pr_fmt
+#define pr_fmt(fmt) "SECBOOT_TPM: " fmt
+#endif
+
+#include <stdlib.h>
+#include <skiboot.h>
+#include <opal.h>
+#include <mbedtls/sha256.h>
+#include "../secvar.h"
+#include "../secvar_devtree.h"
+#include "secboot_tpm.h"
+#include <tssskiboot.h>
+#include <ibmtss/TPM_Types.h>
+
+#define CYCLE_BIT(b) (b^0x1)
+
+#define SECBOOT_TPM_MAX_VAR_SIZE	8192
+
+struct secboot *secboot_image = NULL;
+struct tpmnv_vars *tpmnv_vars_image = NULL;
+struct tpmnv_control *tpmnv_control_image = NULL;
+
+const size_t tpmnv_vars_size = 2048;
+
+/* Expected TPM NV index name field from NV_ReadPublic given our known
+ * set of attributes (see tss_nv_define_space).
+ * See Part 1 Section 16, and Part 2 Section 13.5 of the TPM Specification
+ * for how this is calculated
+ *
+ * These hashes are calculated and checked BEFORE TPM2_NV_WriteLock is called,
+ * which alters the hash slightly as it sets TPMA_NV_WRITELOCKED
+ */
+const uint8_t tpmnv_vars_name[] = {
+        0x00, 0x0b, 0x7a, 0xdb, 0x70, 0xdd, 0x27, 0x94, 0x93, 0x26, 0x11, 0xe2, 0x97,
+        0x00, 0x77, 0x22, 0x4d, 0x5a, 0x74, 0xf8, 0x91, 0x6f, 0xbf, 0xf8, 0x51, 0x4a,
+        0x67, 0x6f, 0xd9, 0xa8, 0xc3, 0xfc, 0x39, 0xed,
+};
+
+const uint8_t tpmnv_control_name[] = {
+	0x00, 0x0b, 0xad, 0x47, 0x6b, 0xa5, 0xdf, 0xb1, 0xe2, 0x18, 0x50, 0xf6, 0x05,
+	0x67, 0xe8, 0x8b, 0xa9, 0x0f, 0x86, 0x1f, 0x06, 0xab, 0x43, 0x96, 0x7f, 0x6e,
+	0x85, 0x33, 0x5b, 0xa6, 0xf0, 0x63, 0x73, 0xd0,
+};
+
+const uint8_t tpmnv_vars_prov_name[] = {
+	0x00, 0x0b, 0x58, 0x36, 0x2c, 0xbf, 0xec, 0x0e, 0xcc, 0xbf, 0xa9, 0x41, 0x94,
+	0xe9, 0x95, 0xe8, 0x3b, 0xd7, 0x8b, 0x52, 0xac, 0x61, 0x6f, 0xe6, 0x42, 0x93,
+	0xbb, 0x5a, 0x79, 0x9f, 0xcc, 0x60, 0x5e, 0x8d,
+};
+
+const uint8_t tpmnv_control_prov_name[] = {
+	0x00, 0x0b, 0x7b, 0xd6, 0x02, 0xac, 0xf5, 0x34, 0x54, 0x5c, 0x3e, 0xda, 0xe5,
+	0xb2, 0xe4, 0x93, 0x4f, 0x36, 0xfb, 0x7f, 0xea, 0xbe, 0xfa, 0x3c, 0xfe, 0xed,
+	0x6a, 0x12, 0xfb, 0xc8, 0xf7, 0x92, 0x0e, 0xd3,
+};
+
+/* Calculate a SHA256 hash over the supplied buffer */
+static int calc_bank_hash(char *target_hash, const char *source_buf, uint64_t size)
+{
+	mbedtls_sha256_context ctx;
+	int rc;
+
+	mbedtls_sha256_init(&ctx);
+
+	rc = mbedtls_sha256_update_ret(&ctx, source_buf, size);
+	if (rc)
+		goto out;
+
+	mbedtls_sha256_finish_ret(&ctx, target_hash);
+	if (rc)
+		goto out;
+
+out:
+	mbedtls_sha256_free(&ctx);
+	return rc;
+}
+
+/* Reformat the TPMNV space */
+static int tpmnv_format(void)
+{
+	int rc;
+
+	memset(tpmnv_vars_image, 0x00, tpmnv_vars_size);
+	memset(tpmnv_control_image, 0x00, sizeof(struct tpmnv_control));
+
+	tpmnv_vars_image->header.magic_number = SECBOOT_MAGIC_NUMBER;
+	tpmnv_vars_image->header.version = SECBOOT_VERSION;
+	tpmnv_control_image->header.magic_number = SECBOOT_MAGIC_NUMBER;
+	tpmnv_control_image->header.version = SECBOOT_VERSION;
+
+	/* Counts as first write to the TPM NV, which sets the
+	 *  TPMA_NVA_WRITTEN attribute */
+	rc = tpmnv_ops.write(SECBOOT_TPMNV_VARS_INDEX,
+			     tpmnv_vars_image,
+			     tpmnv_vars_size, 0);
+	if (rc) {
+		prlog(PR_ERR, "Could not write new formatted data to VARS index, rc=%d\n", rc);
+		return rc;
+	}
+
+	rc = tpmnv_ops.write(SECBOOT_TPMNV_CONTROL_INDEX,
+			     tpmnv_control_image,
+			     sizeof(struct tpmnv_control), 0);
+	if (rc)
+		prlog(PR_ERR, "Could not write new formatted data to CONTROL index, rc=%d\n", rc);
+
+	return rc;
+}
+
+/* Reformat the secboot PNOR space */
+static int secboot_format(void)
+{
+	int rc;
+
+	memset(secboot_image, 0x00, sizeof(struct secboot));
+
+	secboot_image->header.magic_number = SECBOOT_MAGIC_NUMBER;
+	secboot_image->header.version = SECBOOT_VERSION;
+
+	/* Write the hash of the empty bank to the tpm so future loads work */
+	rc = calc_bank_hash(tpmnv_control_image->bank_hash[0],
+			    secboot_image->bank[0],
+			    SECBOOT_VARIABLE_BANK_SIZE);
+	if (rc) {
+		prlog(PR_ERR, "Bank hash failed to calculate somehow\n");
+		return rc;
+	}
+
+	rc = tpmnv_ops.write(SECBOOT_TPMNV_CONTROL_INDEX,
+			     tpmnv_control_image->bank_hash[0],
+			     SHA256_DIGEST_SIZE,
+			     offsetof(struct tpmnv_control,
+			     bank_hash[0]));
+	if (rc) {
+		prlog(PR_ERR, "Could not write fresh formatted bank hashes to CONTROL index, rc=%d\n", rc);
+		return rc;
+	}
+
+	rc = flash_secboot_write(0, secboot_image, sizeof(struct secboot));
+	if (rc)
+		prlog(PR_ERR, "Could not write formatted data to PNOR, rc=%d\n", rc);
+
+	return rc;
+}
+
+
+/*
+ * Serialize one variable to a target memory location.
+ * Returns the advanced target pointer,
+ *   NULL if advanced pointer would exceed the supplied bound
+ */
+static char *secboot_serialize_secvar(char *target, const struct secvar *var, const char *end)
+{
+	if ((target + sizeof(uint64_t) + sizeof(uint64_t)
+		+ var->key_len + var->data_size) > end)
+		return NULL;
+
+	*((uint64_t*) target) = cpu_to_be64(var->key_len);
+	target += sizeof(var->key_len);
+	*((uint64_t*) target) = cpu_to_be64(var->data_size);
+	target += sizeof(var->data_size);
+	memcpy(target, var->key, var->key_len);
+	target += var->key_len;
+	memcpy(target, var->data, var->data_size);
+	target += var->data_size;
+
+	return target;
+}
+
+
+/* Flattens a linked-list bank into a contiguous buffer for writing */
+static int secboot_serialize_bank(const struct list_head *bank, char *target,
+				  size_t target_size, int flags)
+{
+	struct secvar *var;
+	char *end = target + target_size;
+
+	assert(bank);
+	assert(target);
+
+	memset(target, 0x00, target_size);
+
+	list_for_each(bank, var, link) {
+		if (var->flags != flags)
+			continue;
+
+		target = secboot_serialize_secvar(target, var, end);
+		if (!target) {
+			prlog(PR_ERR, "Ran out of %s space, giving up!",
+				(flags & SECVAR_FLAG_PROTECTED) ? "TPMNV" : "PNOR");
+			return OPAL_EMPTY;
+		}
+	}
+
+	return OPAL_SUCCESS;
+}
+
+/* Helper for the variable-bank specific writing logic */
+static int secboot_tpm_write_variable_bank(const struct list_head *bank)
+{
+	int rc;
+	uint64_t bit;
+
+	bit = CYCLE_BIT(tpmnv_control_image->active_bit);
+	/* Serialize TPMNV variables */
+	rc = secboot_serialize_bank(bank, tpmnv_vars_image->vars, tpmnv_vars_size - sizeof(struct tpmnv_vars), SECVAR_FLAG_PROTECTED);
+	if (rc)
+		goto out;
+
+
+	/* Write TPMNV variables to actual NV */
+	rc = tpmnv_ops.write(SECBOOT_TPMNV_VARS_INDEX, tpmnv_vars_image, tpmnv_vars_size, 0);
+	if (rc)
+		goto out;
+
+	/* Serialize the PNOR variables, but don't write to flash until after the bank hash */
+	rc = secboot_serialize_bank(bank, secboot_image->bank[bit], SECBOOT_VARIABLE_BANK_SIZE, 0);
+	if (rc)
+		goto out;
+
+	/* Calculate the bank hash, and write to TPM NV */
+	rc = calc_bank_hash(tpmnv_control_image->bank_hash[bit], secboot_image->bank[bit], SECBOOT_VARIABLE_BANK_SIZE);
+	if (rc)
+		goto out;
+
+	rc = tpmnv_ops.write(SECBOOT_TPMNV_CONTROL_INDEX, tpmnv_control_image->bank_hash[bit],
+				SHA256_DIGEST_LENGTH, offsetof(struct tpmnv_control, bank_hash[bit]));
+	if (rc)
+		goto out;
+
+	/* Write new variable bank to pnor */
+	rc = flash_secboot_write(0, secboot_image, sizeof(struct secboot));
+	if (rc)
+		goto out;
+
+	/* Flip the bit, and write to TPM NV */
+	tpmnv_control_image->active_bit = bit;
+	rc = tpmnv_ops.write(SECBOOT_TPMNV_CONTROL_INDEX,
+			     &tpmnv_control_image->active_bit,
+			     sizeof(tpmnv_control_image->active_bit),
+			     offsetof(struct tpmnv_control, active_bit));
+out:
+
+	return rc;
+}
+
+static int secboot_tpm_write_bank(struct list_head *bank, int section)
+{
+	int rc;
+
+	switch (section) {
+	case SECVAR_VARIABLE_BANK:
+		rc = secboot_tpm_write_variable_bank(bank);
+		break;
+	case SECVAR_UPDATE_BANK:
+		memset(secboot_image->update, 0, SECBOOT_UPDATE_BANK_SIZE);
+		rc = secboot_serialize_bank(bank, secboot_image->update,
+					    SECBOOT_UPDATE_BANK_SIZE, 0);
+		if (rc)
+			break;
+
+		rc = flash_secboot_write(0, secboot_image,
+					    sizeof(struct secboot));
+		break;
+	default:
+		rc = OPAL_HARDWARE;
+	}
+
+	return rc;
+}
+
+
+/*
+ * Deserialize a single secvar from a buffer.
+ * Returns an advanced pointer, and an allocated secvar in *var.
+ * Returns NULL if out of bounds reached, or out of memory.
+ */
+static int secboot_deserialize_secvar(struct secvar **var, char **src, const char *end)
+{
+	uint64_t key_len;
+	uint64_t data_size;
+	struct secvar *ret;
+
+	assert(var);
+
+	/* Load in the two header values */
+	key_len = be64_to_cpu(*((uint64_t *) *src));
+	*src += sizeof(uint64_t);
+	data_size = be64_to_cpu(*((uint64_t *) *src));
+	*src += sizeof(uint64_t);
+
+	/* Check if we've reached the last var to deserialize */
+	if ((key_len == 0) && (data_size == 0)) {
+		return OPAL_EMPTY;
+	}
+
+	if (key_len > SECVAR_MAX_KEY_LEN) {
+		prlog(PR_ERR, "Deserialization failed: key length exceeded maximum value"
+			"%llu > %u", key_len, SECVAR_MAX_KEY_LEN);
+		return OPAL_RESOURCE;
+	}
+	if (data_size > SECBOOT_TPM_MAX_VAR_SIZE) {
+		prlog(PR_ERR, "Deserialization failed: data size exceeded maximum value"
+			"%llu > %u", key_len, SECBOOT_TPM_MAX_VAR_SIZE);
+		return OPAL_RESOURCE;
+	}
+
+	/* Make sure these fields aren't oversized... */
+	if ((*src + key_len + data_size) > end) {
+		*var = NULL;
+		prlog(PR_ERR, "key_len or data_size exceeded the expected bounds");
+		return OPAL_RESOURCE;
+	}
+
+	ret = alloc_secvar(key_len, data_size);
+	if (!ret) {
+		*var = NULL;
+		prlog(PR_ERR, "Out of memory, could not allocate new secvar");
+		return OPAL_NO_MEM;
+	}
+
+	/* Load in variable-sized data */
+	memcpy(ret->key, *src, ret->key_len);
+	*src += ret->key_len;
+	memcpy(ret->data, *src, ret->data_size);
+	*src += ret->data_size;
+
+	*var = ret;
+
+	return OPAL_SUCCESS;
+}
+
+
+/* Load variables from a flattened buffer into a bank list */
+static int secboot_tpm_deserialize_from_buffer(struct list_head *bank, char *src,
+					       uint64_t size, uint64_t flags)
+{
+	struct secvar *var;
+	char *cur;
+	char *end;
+	int rc = 0;
+
+	cur = src;
+	end = src + size;
+
+	while (cur < end) {
+		/* Ensure there is enough space to even check for another var header */
+		if ((end - cur) < (sizeof(uint64_t) * 2))
+			break;
+
+		rc = secboot_deserialize_secvar(&var, &cur, end);
+		switch (rc) {
+			case OPAL_RESOURCE:
+			case OPAL_NO_MEM:
+				goto fail;
+			case OPAL_EMPTY:
+				goto done;
+			default: assert(1);
+		}
+
+		var->flags |= flags;
+
+		list_add_tail(bank, &var->link);
+	}
+done:
+	return OPAL_SUCCESS;
+fail:
+	clear_bank_list(bank);
+	return rc;
+}
+
+static int secboot_tpm_load_variable_bank(struct list_head *bank)
+{
+	char bank_hash[SHA256_DIGEST_LENGTH];
+	uint64_t bit = tpmnv_control_image->active_bit;
+	int rc;
+
+	/* Check the hash of the bank we loaded from PNOR
+	 *  versus the expected hash in TPM NV */
+	rc = calc_bank_hash(bank_hash,
+			    secboot_image->bank[bit],
+			    SECBOOT_VARIABLE_BANK_SIZE);
+	if (rc)
+		return rc;
+
+	if (memcmp(bank_hash,
+		   tpmnv_control_image->bank_hash[bit],
+		   SHA256_DIGEST_LENGTH))
+		/* Tampered pnor space detected, abandon ship */
+		return OPAL_PERMISSION;
+
+	rc = secboot_tpm_deserialize_from_buffer(bank, tpmnv_vars_image->vars, tpmnv_vars_size, SECVAR_FLAG_PROTECTED);
+	if (rc)
+		return rc;
+
+	return secboot_tpm_deserialize_from_buffer(bank, secboot_image->bank[bit], SECBOOT_VARIABLE_BANK_SIZE, 0);
+}
+
+
+static int secboot_tpm_load_bank(struct list_head *bank, int section)
+{
+	switch (section) {
+	case SECVAR_VARIABLE_BANK:
+		return secboot_tpm_load_variable_bank(bank);
+	case SECVAR_UPDATE_BANK:
+		return secboot_tpm_deserialize_from_buffer(bank, secboot_image->update, SECBOOT_UPDATE_BANK_SIZE, 0);
+	}
+
+	return OPAL_HARDWARE;
+}
+
+static int secboot_tpm_get_tpmnv_names(char *nv_vars_name, char *nv_control_name)
+{
+	TPMS_NV_PUBLIC nv_public; /* Throwaway, we only want the name field */
+	TPM2B_NAME vars_tmp;
+	TPM2B_NAME control_tmp;
+	int rc;
+
+	rc = tpmnv_ops.readpublic(SECBOOT_TPMNV_VARS_INDEX,
+				  &nv_public,
+				  &vars_tmp);
+	if (rc) {
+		prlog(PR_ERR, "Failed to readpublic from the VARS index, rc=%d\n", rc);
+		return rc;
+	}
+	rc = tpmnv_ops.readpublic(SECBOOT_TPMNV_CONTROL_INDEX,
+				  &nv_public,
+				  &control_tmp);
+	if (rc) {
+		prlog(PR_ERR, "Failed to readpublic from the CONTROL index, rc=%d\n", rc);
+		return rc;
+	}
+
+	memcpy(nv_vars_name, vars_tmp.t.name, MIN(sizeof(tpmnv_vars_name), vars_tmp.t.size));
+	memcpy(nv_control_name, control_tmp.t.name, MIN(sizeof(tpmnv_control_name), control_tmp.t.size));
+
+	return OPAL_SUCCESS;
+}
+
+
+/* Ensure the NV indices were defined with the correct set of attributes */
+static int secboot_tpm_check_tpmnv_attrs(char *nv_vars_name, char *nv_control_name)
+{
+	if (memcmp(tpmnv_vars_name,
+		   nv_vars_name,
+		   sizeof(tpmnv_vars_name))) {
+		prlog(PR_ERR, "VARS index not defined with the correct attributes\n");
+		return OPAL_RESOURCE;
+	}
+	if (memcmp(tpmnv_control_name,
+		   nv_control_name,
+		   sizeof(tpmnv_control_name))) {
+		prlog(PR_ERR, "CONTROL index not defined with the correct attributes\n");
+		return OPAL_RESOURCE;
+	}
+
+	return OPAL_SUCCESS;
+}
+
+static bool secboot_tpm_check_provisioned_indices(char *nv_vars_name, char *nv_control_name)
+{
+	/* Check for provisioned NV indices, redefine them if detected. */
+	if (!memcmp(tpmnv_vars_prov_name,
+			nv_vars_name,
+			sizeof(tpmnv_vars_prov_name))  &&
+		!memcmp(tpmnv_control_prov_name,
+			nv_control_name,
+			sizeof(tpmnv_control_prov_name))) {
+		return true;
+	}
+
+	/*
+	 * If one matches but the other doesn't, do NOT redefine.
+	 * The next step should detect they don't match the expected values
+	 * and fail the boot.
+	 */
+	return false;
+}
+
+static int secboot_tpm_define_indices(void)
+{
+	int rc = OPAL_SUCCESS;
+
+	rc = tpmnv_ops.definespace(SECBOOT_TPMNV_VARS_INDEX, tpmnv_vars_size);
+	if (rc) {
+		prlog(PR_ERR, "Failed to define the VARS index, rc=%d\n", rc);
+		return rc;
+	}
+
+	rc = tpmnv_ops.definespace(SECBOOT_TPMNV_CONTROL_INDEX, sizeof(struct tpmnv_control));
+	if (rc) {
+		prlog(PR_ERR, "Failed to define the CONTROL index, rc=%d\n", rc);
+		return rc;
+	}
+
+	rc = tpmnv_format();
+	if (rc)
+		return rc;
+
+	/* TPM NV just got redefined, so unconditionally format the SECBOOT partition */
+	return secboot_format();
+}
+
+static int secboot_tpm_undefine_indices(bool *vars_defined, bool *control_defined)
+{
+	int rc;
+
+	if (vars_defined) {
+		rc = tpmnv_ops.undefinespace(SECBOOT_TPMNV_VARS_INDEX);
+		if (rc) {
+			prlog(PR_ERR, "Failed to undefine VARS, something is seriously wrong\n");
+			return rc;
+		}
+	}
+
+	if (control_defined) {
+		rc = tpmnv_ops.undefinespace(SECBOOT_TPMNV_CONTROL_INDEX);
+		if (rc) {
+			prlog(PR_ERR, "Failed to undefine CONTROL, something is seriously wrong\n");
+			return rc;
+		}
+	}
+
+	*vars_defined = *control_defined = false;
+
+	return OPAL_SUCCESS;
+}
+
+
+static int secboot_tpm_store_init(void)
+{
+	int rc;
+	unsigned int secboot_size;
+
+	TPMI_RH_NV_INDEX *indices = NULL;
+	char nv_vars_name[sizeof(tpmnv_vars_name)];
+	char nv_control_name[sizeof(tpmnv_control_name)];
+	size_t count = 0;
+	bool control_defined = false;
+	bool vars_defined = false;
+	int i;
+
+	if (secboot_image)
+		return OPAL_SUCCESS;
+
+	prlog(PR_DEBUG, "Initializing for pnor+tpm based platform\n");
+
+	/* Initialize SECBOOT first, we may need to format this later */
+	rc = flash_secboot_info(&secboot_size);
+	if (rc) {
+		prlog(PR_ERR, "error %d retrieving keystore info\n", rc);
+		goto error;
+	}
+	if (sizeof(struct secboot) > secboot_size) {
+		prlog(PR_ERR, "secboot partition %d KB too small. min=%ld\n",
+		      secboot_size >> 10, sizeof(struct secboot));
+		rc = OPAL_RESOURCE;
+		goto error;
+	}
+
+	secboot_image = memalign(0x1000, sizeof(struct secboot));
+	if (!secboot_image) {
+		prlog(PR_ERR, "Failed to allocate space for the secboot image\n");
+		rc = OPAL_NO_MEM;
+		goto error;
+	}
+
+	/* Read in the PNOR data, bank hash is checked on call to .load_bank() */
+	rc = flash_secboot_read(secboot_image, 0, sizeof(struct secboot));
+	if (rc) {
+		prlog(PR_ERR, "failed to read the secboot partition, rc=%d\n", rc);
+		goto error;
+	}
+
+	/* Allocate the tpmnv data buffers */
+	tpmnv_vars_image = zalloc(tpmnv_vars_size);
+	if (!tpmnv_vars_image)
+		return OPAL_NO_MEM;
+	tpmnv_control_image = zalloc(sizeof(struct tpmnv_control));
+	if (!tpmnv_control_image)
+		return OPAL_NO_MEM;
+
+	/* Check if the NV indices have been defined already */
+	rc = tpmnv_ops.getindices(&indices, &count);
+	if (rc) {
+		prlog(PR_ERR, "Could not load defined indicies from TPM, rc=%d\n", rc);
+		goto error;
+	}
+
+	for (i = 0; i < count; i++) {
+		if (indices[i] == SECBOOT_TPMNV_VARS_INDEX)
+			vars_defined = true;
+		else if (indices[i] == SECBOOT_TPMNV_CONTROL_INDEX)
+			control_defined = true;
+	}
+	free(indices);
+
+	/* Undefine the NV indices if physical presence has been asserted */
+	if (secvar_check_physical_presence()) {
+		prlog(PR_INFO, "Physical presence asserted, redefining NV indices, and resetting keystore\n");
+		rc = secboot_tpm_undefine_indices(&vars_defined, &control_defined);
+		if (rc)
+			goto error;
+
+		rc = secboot_tpm_define_indices();
+		if (rc)
+			goto error;
+
+		/* Indices got defined and formatted, we're done here */
+		goto done;
+	}
+	/* Determine if we need to define the indices. These should BOTH be false or true */
+	if (!vars_defined && !control_defined) {
+		rc = secboot_tpm_define_indices();
+		if (rc)
+			goto error;
+
+		/* Indices got defined and formatted, we're done here */
+		goto done;
+	}
+	if (vars_defined ^ control_defined) {
+		/* This should never happen. Both indices should be defined at the same
+		 * time. Otherwise something seriously went wrong. */
+		prlog(PR_ERR, "NV indices defined with unexpected attributes. Assert physical presence to clear\n");
+		goto error;
+	}
+
+	/* Both indices are defined, now need to validate their contents */
+
+	rc = secboot_tpm_get_tpmnv_names(nv_vars_name, nv_control_name);
+	if (rc)
+		goto error;
+
+	/* Check for provisioned TPMNV indices, redefine them if detected */
+	if (secboot_tpm_check_provisioned_indices(nv_vars_name, nv_control_name)) {
+		prlog(PR_INFO, "Provisioned TPM NV indices detected, redefining NV indices, and resetting keystore\n");
+		rc = secboot_tpm_undefine_indices(&vars_defined, &control_defined);
+		if (rc)
+			goto error;
+
+		rc = secboot_tpm_define_indices();
+		if (rc)
+			goto error;
+
+		/* Indices got defined and formatted, we're done here */
+		goto done;
+	}
+
+	/* Otherwise, ensure the NV indices were defined with the correct set of attributes */
+	rc = secboot_tpm_check_tpmnv_attrs(nv_vars_name, nv_control_name);
+	if (rc)
+		goto error;
+
+
+	/* TPMNV indices exist, are correct, and weren't just formatted, so read them in */
+	rc = tpmnv_ops.read(SECBOOT_TPMNV_VARS_INDEX,
+			    tpmnv_vars_image,
+			    tpmnv_vars_size, 0);
+	if (rc) {
+		prlog(PR_ERR, "Failed to read from the VARS index\n");
+		goto error;
+	}
+
+	rc = tpmnv_ops.read(SECBOOT_TPMNV_CONTROL_INDEX,
+			    tpmnv_control_image,
+			    sizeof(struct tpmnv_control), 0);
+	if (rc) {
+		prlog(PR_ERR, "Failed to read from the CONTROL index\n");
+		goto error;
+	}
+
+	/* Verify the header information is correct */
+	if (tpmnv_vars_image->header.magic_number != SECBOOT_MAGIC_NUMBER ||
+	    tpmnv_control_image->header.magic_number != SECBOOT_MAGIC_NUMBER ||
+	    tpmnv_vars_image->header.version != SECBOOT_VERSION ||
+	    tpmnv_control_image->header.version != SECBOOT_VERSION) {
+		prlog(PR_ERR, "TPMNV indices defined, but contain bad data. Assert physical presence to clear\n");
+		goto error;
+	}
+
+	/* Verify the secboot partition header information,
+	 *  reformat if incorrect
+	 * Note: Future variants should attempt to handle older versions safely
+	 */
+	if (secboot_image->header.magic_number != SECBOOT_MAGIC_NUMBER ||
+	    secboot_image->header.version != SECBOOT_VERSION) {
+		rc = secboot_format();
+		if (rc)
+			goto error;
+	}
+
+done:
+	return OPAL_SUCCESS;
+
+error:
+	free(secboot_image);
+	secboot_image = NULL;
+	free(tpmnv_vars_image);
+	tpmnv_vars_image = NULL;
+	free(tpmnv_control_image);
+	tpmnv_control_image = NULL;
+
+	return rc;
+}
+
+
+static void secboot_tpm_lockdown(void)
+{
+	/* Note: While write lock is called here on the two NV indices,
+	 * both indices are also defined on the platform hierarchy.
+	 * The platform hierarchy auth is set later in the skiboot
+	 * initialization process, and not by any secvar-related code.
+	 */
+	int rc;
+
+	rc = tpmnv_ops.writelock(SECBOOT_TPMNV_VARS_INDEX);
+	if (rc) {
+		prlog(PR_EMERG, "TSS Write Lock failed on VARS index, halting.\n");
+		abort();
+	}
+
+	rc = tpmnv_ops.writelock(SECBOOT_TPMNV_CONTROL_INDEX);
+	if (rc) {
+		prlog(PR_EMERG, "TSS Write Lock failed on CONTROL index, halting.\n");
+		abort();
+	}
+}
+
+struct secvar_storage_driver secboot_tpm_driver = {
+	.load_bank = secboot_tpm_load_bank,
+	.write_bank = secboot_tpm_write_bank,
+	.store_init = secboot_tpm_store_init,
+	.lockdown = secboot_tpm_lockdown,
+	.max_var_size = SECBOOT_TPM_MAX_VAR_SIZE,
+};